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Carl Nelson, computer memory, and the EESU « Scientific Information « Technology
 
Sun, 01 Jan 2012, 12:37pm #61
ee-tom
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Technopete wrote:

ee-tom wrote:

TP - DRP has a comprehensive qualitative understanding of physics. He is using this to understand what is going on from a superior vantage point, not distracted by the details which obsess you.
....
Some people might think that the EEstor mystery is fundamentally, and obviously, quantitative - but then perhaps if they had DRPs comprehensive qualitative understanding of physics they would know better?
Too subtle. Not a chance that anyone here will understand what you are saying.

No-one even got my "Wunch of Bankers" joke in chat a couple of weeks ago.

Regards,
Peter

I must remember that - quite a good collective noun.


Assumptions: 1) E=1/2CV2

(Only dummies assume this)

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Tue, 03 Jan 2012, 9:49am #62
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Technopete wrote:

Whether DAP agrees or not with the conclusion that the alumina cannot store most of the energy, he should now at least see why the maths says it is not likely to be so.


As noted before, I agree that the maths indicate alumina can only account for a fraction of the stored energy. In my mind the question comes down to - what causes the fields? (Or even, as noted in post #52, what are the fields?).

I’m still not a believer (a minority of one it seems) that the stored energy is a result of a constant static voltage between the aluminum plates. My argument is simple. Since poling establishes trapped dipoles (electrets) in the PET, continuous exposure of PET to a high field will result in charge detrapping and recombination. Such recombination can either be radiative (producing photons) or non-radiative (producing phonons). In order to keep leakage down to the level claimed by Eestor, the process of recovering energy from these photons/phonons by the aluminum plates would have to absolute.

Last edited Tue, 03 Jan 2012, 10:05am by DAP


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Tue, 03 Jan 2012, 11:38am #63
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DAP wrote:

Technopete wrote:

Whether DAP agrees or not with the conclusion that the alumina cannot store most of the energy, he should now at least see why the maths says it is not likely to be so.


As noted before, I agree that the maths indicate alumina can only account for a fraction of the stored energy. In my mind the question comes down to - what causes the fields? (Or even, as noted in post #52, what are the fields?).

I’m still not a believer (a minority of one it seems) that the stored energy is a result of a constant static voltage between the aluminum plates. My argument is simple. Since poling establishes trapped dipoles (electrets) in the PET, continuous exposure of PET to a high field will result in charge detrapping and recombination. Such recombination can either be radiative (producing photons) or non-radiative (producing phonons). In order to keep leakage down to the level claimed by Eestor, the process of recovering energy from these photons/phonons by the aluminum plates would have to absolute.

DAP,

There's only around 4% of PET in there (by volume). Even if 4% of the incoming energy gets converted to heat by things happening in the PET, that would not be much of a problem. OK, we would prefer such things not to happen (and they probably don't, even to 4% of the input energy), but it's not a major issue compared with storage of 96+% of the energy elsewhere as some sort of polarisation.

Incidentally, similar maths applies to the PET as applies to the alumina when calculating upper bounds of energy stored in various materials. Personally I believe the PET tends to be in sheets between columns of coated CMBT, and that it has a lower polarisation than these columns, but even if it polarises to 60C/m2 you can still use the formula for working out what the maximum percentage of energy in the PET would be if you stick to the breakdown voltage of PET in the patent.

Regards,
Peter


Assumptions: 1) E=1/2CV2. (Only dummies assume this). (I am one of these dummies).

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Tue, 03 Jan 2012, 11:59am #64
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Technopete wrote:

DAP wrote:

Technopete wrote:

Whether DAP agrees or not with the conclusion that the alumina cannot store most of the energy, he should now at least see why the maths says it is not likely to be so.


As noted before, I agree that the maths indicate alumina can only account for a fraction of the stored energy. In my mind the question comes down to - what causes the fields? (Or even, as noted in post #52, what are the fields?).

I’m still not a believer (a minority of one it seems) that the stored energy is a result of a constant static voltage between the aluminum plates. My argument is simple. Since poling establishes trapped dipoles (electrets) in the PET, continuous exposure of PET to a high field will result in charge detrapping and recombination. Such recombination can either be radiative (producing photons) or non-radiative (producing phonons). In order to keep leakage down to the level claimed by Eestor, the process of recovering energy from these photons/phonons by the aluminum plates would have to absolute.

DAP,

There's only around 4% of PET in there (by volume). Even if 4% of the incoming energy gets converted to heat by things happening in the PET, that would not be much of a problem. OK, we would prefer such things not to happen (and they probably don't, even to 4% of the input energy), but it's not a major issue compared with storage of 96+% of the energy elsewhere as some sort of polarisation.
...


Really? The issue is leakage. I haven’t applied any maths to this yet, but my guess is that if 0.16% of the energy (or any energy for that matter) in the field established by a static voltage between the aluminum plates is lost to heat then the resulting leakage would be a major problem. Such loss would be continuous (at least to that point where the voltage was reduced to an amount that would no longer drive charge detrapping and subsequent recombination).

Last edited Tue, 03 Jan 2012, 12:18pm by DAP


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Tue, 03 Jan 2012, 12:08pm #65
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DAP wrote:

It’s New Year’s Eve. I guess now is the time for the punch line (hinted at in post # 33).

This thread started out with the observation that Carl Nelson and Dick Weir have a long running familiarity with computer memory, in particular with the use of Field Effect Transistor technology in non-volatile memory. Perhaps this familiarity has nothing to do with Eestor’s energy storage mechanism, just like the term ‘paramagnetic’ that started appearing in Eestor’s patent applications is nothing more than a typographical error.

ee-tom wrote:

There is also a certain strand of comment here which is unfortunate because it might give naive readers an unwarranted sense that there exists some scientific rationale for DWs words.

As Y_Po & I have pointed out, paramagnetic is not significant, except as indication that late at night DW gets those long words confused.

Ah yes, what can be done about us poor “naïve readers?” (And, worse yet, what can be done about us even more naïve posters?) We are the poor schmucks who keep banging away, trying to figure out if the ‘impossible dream’ of an EESU has any scientific rationale at all. We stumble forward attempting to understand some principles and concepts of solid state physics while others assure us that none of this effort really matters. Before we ring in the New Year, however, I would like to add one more personality (and the associated concepts) for our ranks to consider – Alexander Khitun. Apparently DARPA and the NSF think highly enough of Khitun's work to throw money his way (For example, see Magnetic Logic Attracts Money & Khitun is Co-PI on $1.55M NSF Award-Winning Team). [For links to more basic related research see Retrospective—Electromagnons offer the best of two worlds & Magnetic field induced dehybridization of the electromagnons in multiferroic TbMnO3.

But what has any of this have to do with energy storage devices like the EESU? The punch line is that UCLA is trying to parlay Khitun’s expertise in computer memory and spin waves into the energy storage field as well. See Electric Capacitor Utilizing The Self-capacitance Of Conducting Nanoparticles

The invention disclosed is a novel capacitor that can store energy 100 times more efficiently than the best supercapacitors on the market. It provides a large total capacitance through the self-capacitance in an array of conducting nanoparticles. The result is a capacitor that can store energy in a density close to that of gasoline. For a particular power desired, this invention allows for smaller and lighter batteries than conventional capacitors can provide.

Energy density two orders of magnitude higher than conventional capacitors

Energy storage: 2x105 Joules/Liter (gasoline has 5.8 x105 J/L and today’s supercapacitors have 2000 J/L)

It would appear that Dick Weir is not the only one pursuing the ‘impossible dream’ of a high-energy density ceramic capacitive device. If you are naïve enough to believe that Khitun actually has something, I suppose you might as well also be naïve enough to have “an unwarranted sense that there exists some scientific rationale” for DW’s use of the term ‘paramagnetic.’


From Retrospective—Electromagnons offer the best of two worlds
It is now known that electromagnons can be in multiferroics where ferroelectricity does not arise from magnetic order. For example, these excitations occur in multiferroic , where ferroelectricity arises from the lone-pair mechanism and a low-pitch antiferromagnetic spiral does not form except at a much lower temperature [5]. Recently (and somewhat surprisingly), electromagnons were reported in the paraelectric phase of multiferroic materials. For example, electromagnons have been observed in a very different material with a very different electronic and physical structure: a conical-spin magnetically ordered phase of the paraelectric phase of the hexaferrite. This is an exciting discovery, as it suggests that electric-dipole-active magnons can exist in nonmultiferroic materials, and that many magnetically ordered insulators with complex noncollinear magnetic structures may support electromagnon excitations.

One more interesting reference – Gigantic terahertz magnetochromism in hexaferrite magnet Ba2Mg2Fe12O22

The important implication of the present work is that the source of the electromagnon is not limited to multiferroics; electromagnon resonance emerges irrespective of the presence of the ferroelectricity. There are a variety of non collinear magnets at room temperature, which are candidates to potentially host the gigantic magnetochromism via electromagnons.

And from the abstract:
With changing the conical spin structures in terms of the conical angle θ from the proper screw (θ = 0o) to the ferromagnetic (θ = 90o) through the conical spin-ordered phases (0o < θ < 90o) by external magnetic fields, we identify the maximal magnetochromism around θ ≈ 45o.

It may well be that DW/CN found out something about paraelectric (and paramagnetic) CMBT that was unexpected and that (at first) they couldn't explain.

DW wrote:

They all go through 45o

What a curious statement.

Last edited Tue, 03 Jan 2012, 3:03pm by DAP


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Tue, 03 Jan 2012, 12:20pm #66
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Most likely the EESU is going to get warm on charge and discharge, though hopefully it would stay below a limit temperature such as 85 degrees C - a guess which should be substituted by whatever DW put in the patent for upper operating temperature.

Leakage is going to increase when it is warm, but this is for a limited time only - until it cools - provided that the leakage current is not high enough to raise the temperature further when it is already a few degrees above ambient.

Let's say you lose 4% of the energy to heat at an inconvenient point because of losses in the PET. That's 2kWH = 7.2 MegaJoules. I don't know the "specific heat" of an EESU (someone could look up the figure for Barium Titanate), but let's assume it is the same as water which is 4.2 J/gm/degree C. We have 135kg of EESU, so the temperature rise would be :-

7,200,000 / (135,000 x 4.2) = 13 degrees

That's a crude estimate of the temperature rise in the whole EESU if 4% of the energy is converted to heat over a short period without sufficient time to lose heat to the atmosphere through normal cooling. It doesn't seem excessive as these things go. It could be on top of the rise due to charging or discharging, which depends on the efficiency of the EESU, which we don't really know. But even so, it doesn't seem to be enough to produce some sort of thermal runaway by exceeding a limit temperature such as 85 degrees C.

Regards,
Peter


Assumptions: 1) E=1/2CV2. (Only dummies assume this). (I am one of these dummies).

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Tue, 03 Jan 2012, 12:40pm #67
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Technopete wrote:

Most likely the EESU is going to get warm on charge and discharge, though hopefully it would stay below a limit temperature such as 85 degrees C - a guess which should be substituted by whatever DW put in the patent for upper operating temperature.

Leakage is going to increase when it is warm, but this is for a limited time only - until it cools - provided that the leakage current is not high enough to raise the temperature further when it is already a few degrees above ambient.

Let's say you lose 4% of the energy to heat at an inconvenient point because of losses in the PET. That's 2kWH = 7.2 MegaJoules. I don't know the "specific heat" of an EESU (someone could look up the figure for Barium Titanate), but let's assume it is the same as water which is 4.2 J/gm/degree C. We have 135kg of EESU, so the temperature rise would be :-

7,200,000 / (135,000 x 4.2) = 13 degrees

That's a crude estimate of the temperature rise in the whole EESU if 4% of the energy is converted to heat over a short period without sufficient time to lose heat to the atmosphere through normal cooling. It doesn't seem excessive as these things go. It could be on top of the rise due to charging or discharging, which depends on the efficiency of the EESU, which we don't really know. But even so, it doesn't seem to be enough to produce some sort of thermal runaway by exceeding a limit temperature such as 85 degrees C.

Regards,
Peter

Please correct me if I'm wrong but, as I stated before, as long as there is voltage between the aluminum plates the loss would be continuous (at least to that point where the voltage was reduced to an amount that would no longer drive charge detrapping and subsequent recombination). In other words, charge detrapping/recombination is driven not by the generation of a high field but by the presence of a high field.


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Tue, 03 Jan 2012, 3:38pm #68
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If there are any at all then there are a limited number of trapped dipoles in the PET. Once those have been eliminated (maybe over time by a continous DC field), then what more energy can be lost? Once any PET dipoles had recombined then the leakage will go away. There can't be a possibility of any more leakage unless the PET can start conducting charge from the parallel CMBT/alumina material.

Regards,
Peter


Assumptions: 1) E=1/2CV2. (Only dummies assume this). (I am one of these dummies).

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Wed, 04 Jan 2012, 5:08am #69
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Technopete wrote:

I don't know the "specific heat" of an EESU (someone could look up the figure for Barium Titanate), but let's assume it is the same as water which is 4.2 J/gm/degree C.

Using specific heat for water is likely to give a low estimate of the temperature rise.
According to wiki http://en.wikipedia.org/wiki/Heat_capacity titanium is 0.52 J/g/deg.
Barium http://en.wikipedia.org/wiki/Barium is 28 J/mole/deg with an atomic weight of 137 so if I remember my chemisty correctly we end up with a specific heat just over 0.2
Best regards Simon


"nanotechnology is going to be huge" (Lord Sainsbury).

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Wed, 04 Jan 2012, 6:11am #70
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SimonB wrote:

Technopete wrote:

I don't know the "specific heat" of an EESU (someone could look up the figure for Barium Titanate), but let's assume it is the same as water which is 4.2 J/gm/degree C.

Using specific heat for water is likely to give a low estimate of the temperature rise.
According to wiki http://en.wikipedia.org/wiki/Heat_capacity titanium is 0.52 J/g/deg.
Barium http://en.wikipedia.org/wiki/Barium is 28 J/mole/deg with an atomic weight of 137 so if I remember my chemisty correctly we end up with a specific heat just over 0.2
Best regards Simon

Water has an unusually high specific heat because of (I think, but chemists will correct me no doubt) unusual hydrogen bonding between molecules.

BT is 0.44 J/(gK)

it varies a bit with phase, and has a small peak at the FE/PE transition.

Best wishes, Tom


Assumptions: 1) E=1/2CV2

(Only dummies assume this)

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Wed, 04 Jan 2012, 7:26am #71
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Technopete wrote:

If there are any at all then there are a limited number of trapped dipoles in the PET. Once those have been eliminated (maybe over time by a continous DC field), then what more energy can be lost? Once any PET dipoles had recombined then the leakage will go away. There can't be a possibility of any more leakage unless the PET can start conducting charge from the parallel CMBT/alumina material.

Regards,
Peter

This is not the proper way of viewing this. Poled PET is a semiconductor. In other words, it is a mobile charge carrier. The electron-hole dipoles of the PET electrets are traps. Indeed, the poling creates deep-level traps in the PET which promote recombination. Accordingly, it is at these trap locations that mobile electrons (those in the conduction band) recombine with holes. Such recombination does not deplete the PET of electron-hole pairs (the deep-level traps). Nor does it remove all of the mobile electrons (which result from an electron in the valence band acquiring enough energy to be ‘promoted’ to the conduction band). As long as an energy field is present as a result of aluminum electrode voltage, the process of carrier generation and recombination in poled PET will be continuous.

See Carrier generation and recombination.

Regards, dp

Last edited Wed, 04 Jan 2012, 8:49am by DAP


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Wed, 04 Jan 2012, 8:36am #72
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ee-tom wrote:

SimonB wrote:

Technopete wrote:

I don't know the "specific heat" of an EESU (someone could look up the figure for Barium Titanate), but let's assume it is the same as water which is 4.2 J/gm/degree C.

Using specific heat for water is likely to give a low estimate of the temperature rise.
According to wiki http://en.wikipedia.org/wiki/Heat_capacity titanium is 0.52 J/g/deg.
Barium http://en.wikipedia.org/wiki/Barium is 28 J/mole/deg with an atomic weight of 137 so if I remember my chemisty correctly we end up with a specific heat just over 0.2
Best regards Simon

Water has an unusually high specific heat because of (I think, but chemists will correct me no doubt) unusual hydrogen bonding between molecules.

BT is 0.44 J/(gK)

it varies a bit with phase, and has a small peak at the FE/PE transition.

Best wishes, Tom

That's in line with a figure of 0.37 J/g/K for Barium Zirconate from NIST Structural Ceramics Database (SCD).

In which case the EESU temperature rise would be 130 degrees due to 4% of the energy (if that was stored in the PET) being released as heat over a short period of time.

But most likely:-

a) 4% of energy is not stored in the PET - the true figure is almost certainly much lower as it like has a much lower permittivity than the CMBT granules and

b) the leakage current would be low enough that the heat would be dissipated as it is produced, resulting in a much lower temperature rise.

So no thermal runaway.

Regards,
Peter


Assumptions: 1) E=1/2CV2. (Only dummies assume this). (I am one of these dummies).

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Wed, 04 Jan 2012, 8:47am #73
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DAP wrote:

The invention disclosed is a novel capacitor that can store energy 100 times more efficiently than the best supercapacitors on the market. It provides a large total capacitance through the self-capacitance in an array of conducting nanoparticles. The result is a capacitor that can store energy in a density close to that of gasoline. For a particular power desired, this invention allows for smaller and lighter batteries than conventional capacitors can provide.

Energy density two orders of magnitude higher than conventional capacitors

Energy storage: 2x105 Joules/Liter (gasoline has 5.8 x105 J/L and today’s supercapacitors have 2000 J/L)
But
Wikipedia says

Gasoline contains about 35 MJ/L.

This is 3.5 x 107 J/litre = 3.5 x 104 J/cc = 35,000 J/cc.

Further, the EESU contains 10,000 = 104 J/cc which is 107 J/litre.

1 litre = 1000 cc's.

What can the supercapacitor actually store?

p.s. it's the power of ten rather than the significant digits which needs to be clarified here.

Regards,
Peter

Last edited Wed, 04 Jan 2012, 8:54am by Technopete


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Wed, 04 Jan 2012, 9:06am #74
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Technopete wrote:

DAP wrote:

The invention disclosed is a novel capacitor that can store energy 100 times more efficiently than the best supercapacitors on the market. It provides a large total capacitance through the self-capacitance in an array of conducting nanoparticles. The result is a capacitor that can store energy in a density close to that of gasoline. For a particular power desired, this invention allows for smaller and lighter batteries than conventional capacitors can provide.

Energy density two orders of magnitude higher than conventional capacitors

Energy storage: 2x105 Joules/Liter (gasoline has 5.8 x105 J/L and today’s supercapacitors have 2000 J/L)

[T]he EESU contains 10,000 = 104 J/cc which is 107 J/litre.

So Khitun’s stated energy density is only 50x less than that of an EESU. That’s not too shabby! The point I was making, however, is the Khitun’s energy storage is probably based on capacitance and very likely has a magnetoelectric component to it based on his published work (in memory - hence the post referring to Khitun's energy storage claims in this topic).

Last edited Wed, 04 Jan 2012, 9:28am by DAP


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Wed, 04 Jan 2012, 9:26am #75
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I'm amazed by Khitun's claims. His idea is not new to me but it certainly dosen't jump right out at me how he manages to solve the problem of charging and discharging the array as well as other problems whih coud certainly limit the device. If he's making sweeping claims for conducting nanoparticles as a capacitor he is in big trouble.


Nothing in life is certain except death, taxes and the second law of thermodynamics.

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Wed, 04 Jan 2012, 10:00am #76
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Daniel R Plante wrote:

DAP wrote:

devotEE wrote:

In this device the charge is stored on the electrodes.

EEventually wrote:

…The field remains because of the charge on the plates. We call them insulators because they don't move charges.

I respectfully disagree. If Eestor wanted to make their PET/coated-CMBT composite as insulating as possible (therefore ensuring that charge remains on the aluminum plates), they would have never poled it.

See Analysis of electric conduction mechanisms in polyethylene terephthalate. In particular, see Fig. 1 which shows that the repeated cycling of applied high voltage increases the current observed when applying that voltage in later cycles.

I agree more with the following sentiment: http://www.theeestory.com/posts/117061.



Dan, I read the paper and I don't see what you're referring to. The paper basically profiles a very good insulating material, made even better by poling that produces bi-polar space charges. This is basically an electret, and the reduction in leakage current due to the space charges in electrets (in plastics as well as ceramics like alumina) is well documented in the literature.

From figure 1, the leakage current at 1.5 V/um is extraordinarily low at aprox 1.5 pA/cm2 on their 6cm diameter sample (gee, I wonder how they measured 45pA ;)

Even at 20 V/um it's only about 1.5 nA/cm2. The difference between the poled measure of 175 pA and the unpoled measure of 45pA might seem relatively large, but in absolute terms they are equally tiny.

I also don't see any attempt by them to find a space charge saturation point by leaving their moderate (not high) fields applied for a considerable time (minutes to days). If they did they might have noticed an eventual drop in leakage current, or a flattening of the curve with higher applied fields. That was not the focus of their experiment though.
DAP,

In the research paper there seems to be no indication of what units they are using in their graphs of current - is it amps for the whole specimen, amps per square metre, or amps per square cm?

In the absence of any indication perhaps they should be interpreted as current through the specimen.

Since the electrodes extend only over a 5cm diameter, then it is better to use this rather than a 6cm diameter as current cannot flow through an area of specimen without electrodes. So the area through which the current flows is pi x 52 / 4 (to square the radius not the diamter) = 19.6 cm2. Call it 20 cm2 to make all the maths easier. Since there are 10,000 cm2 in a square metre then we must multiply current figures by 500 to get A/m2.

If you assume ohmic behaviour, then around 3 x 10-7 amps for the specimen at 180 volts for 10 um thickness requires we multiply by 500 (for area) and 20 (for voltage compared with 3,600V). The current would then become around 3 x 10-3 A/m2 = 3mA/m2. Since the EESU has 60 coulombs per square metre of charge then at the full voltage 60 C would flow in 60/0.003 seconds = 20,000 seconds or 6 hours through the PET.

Then we have to take into account that the PET represents only say 4%, which increases the time up to 150 hours, or getting on for a week to mostly discharge.

Hopefully DW's PET is much much better than the stuff measured in this paper, or the current measurments are amps per m2 or something . Otherwise the EESU is dead in the water!

So it is easy to see why you might be concerned!!

If the currents are in A/m2 then we can kick off by multiplying by 500, so the discharge times then become around 500 weeks or approximately 10 years, which is more in line with the EESU patent, though not quite as good. That's not the whole story though, as Poole-Frenkel currents rise exponentially with the square root of the voltage rather than linearly.

I've emailed Eugen Neagu to ask for clarification on the scaling of the currents in the graphs.

Regards,
Peter

Last edited Wed, 04 Jan 2012, 10:30am by Technopete


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Wed, 04 Jan 2012, 11:45am #77
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Technopete wrote:

In the research paper there seems to be no indication of what units they are using in their graphs of current - is it amps for the whole specimen, amps per square metre, or amps per square cm?

In the absence of any indication perhaps they should be interpreted as current through the specimen.

If you assume ohmic behaviour, then…

I would not make this assumption at high field. From the conclusion of Analysis of electric conduction mechanisms in polyethylene terephthalate:
Initially the current has an ohmic behavior determined by the movement of electrons and/or ions from the localized states of insulator in the vicinity of the Fermi level of the metal. As the field increases the current changes to a Richardson-Schottky behavior. Though this behavior remains formally true up to high fields, the estimation of the dielectric constant on the basis of the Richardson-Schottky relation leads to unacceptable values. For medium and high fields the bulk processes, i.e., Poole-Frenkel, and the Fowler-Nordheim process, describe the experimental data best.

Your maths may well be comparing apples to oranges, but let’s assume they are correct. The point I was trying to make by pointing out the data in Fig. 1 of the linked-to reference above is that there is charge transport through PET and that by generating space-charge loci in PET, the current through the PET (at low voltages) is changed (in this case, increased).

Technopete wrote:

Then we have to take into account that the PET represents only say 4%, which increases the time up to 150 hours, or getting on for a week to mostly discharge.

Hopefully DW's PET is much much better than the stuff measured in this paper, or the current measurments are amps per m2 or something . Otherwise the EESU is dead in the water!

So it is easy to see why you might be concerned!!

That’s my point. But it is not as simple as it appears. DW’s PET is not much much better. It is much much different. By poling at high voltages and creating deep-level traps (the electrets, which are different than the space-charge phenomena discussed in the linked-to paper), charge transport in the PET should be decreased! The price to be paid for decreasing the charge transport in poled PET is that there will be an increase in photons and/or phonons created by radiative or non-radiative processes, respectively, as a result of the traps. Such deep-level traps can actually be a nuisance in semiconductors for this very reason – they decrease the charge transport. Accordingly, my contention is that in an energy storage paradigm reliant upon a static voltage at the aluminum plates, unless there is complete recovery of this photon and/or phonon energy by these plates the result may be an intolerable amount of leakage.

There is an alternative. And part of this alternative has to do with pulsed DC voltage and an energy storage paradigm in which there is no (or little) charge on the aluminum plates, with energy fields established by other mechanisms in the dielectric composition.


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Wed, 04 Jan 2012, 2:25pm #78
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DAP,

Since there's a 500x difference between two of the leakage current scaling factor options (Amps through sample electrodes vs A/m2) in the linked paper, it would be best to wait for a response from the author before drawing drastic conclusions about how big a problem PET leakage might be.

The point of this is that it is this leakage current that is the conduction of charge which you believe will create electrets in the PET during poling. So if the leakage current is miniscule, then PET electrets will be rare and can only cause minimal leakage after poling.

Regards,
Peter

Last edited Wed, 04 Jan 2012, 6:06pm by Technopete


Assumptions: 1) E=1/2CV2. (Only dummies assume this). (I am one of these dummies).

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Wed, 04 Jan 2012, 10:26pm #79
Daniel R Plante
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Technopete wrote:

If there are any at all then there are a limited number of trapped dipoles in the PET. Once those have been eliminated (maybe over time by a continous DC field), then what more energy can be lost? Once any PET dipoles had recombined then the leakage will go away. There can't be a possibility of any more leakage unless the PET can start conducting charge from the parallel CMBT/alumina material.

Regards,
Peter


Yes. This was my point wrt the empirical literature regarding bi-polar trapped space charge in polymers, ceramics, etc (electrets) and the attendant various theoretical models.


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Wed, 04 Jan 2012, 10:36pm #80
Daniel R Plante
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DAP wrote:

Technopete wrote:

If there are any at all then there are a limited number of trapped dipoles in the PET. Once those have been eliminated (maybe over time by a continous DC field), then what more energy can be lost? Once any PET dipoles had recombined then the leakage will go away. There can't be a possibility of any more leakage unless the PET can start conducting charge from the parallel CMBT/alumina material.

Regards,
Peter

This is not the proper way of viewing this. Poled PET is a semiconductor. In other words, it is a mobile charge carrier. The electron-hole dipoles of the PET electrets are traps. Indeed, the poling creates deep-level traps in the PET which promote recombination. Accordingly, it is at these trap locations that mobile electrons (those in the conduction band) recombine with holes. Such recombination does not deplete the PET of electron-hole pairs (the deep-level traps). Nor does it remove all of the mobile electrons (which result from an electron in the valence band acquiring enough energy to be ‘promoted’ to the conduction band). As long as an energy field is present as a result of aluminum electrode voltage, the process of carrier generation and recombination in poled PET will be continuous.

See Carrier generation and recombination.

Regards, dp



Dan, this process is for the most part, dependant on material temperature and is profoundly self-extinguishing and extraordinarily fleeting. It is inevitable in intrinsic semiconductor material, and insulators as well. This is not conduction band charge carrier availability nor valence band charge carrier availability. The physical explanation for this distinction is beyond the scope of a blog post.


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Wed, 04 Jan 2012, 10:45pm #81
Daniel R Plante
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Technopete wrote:

Daniel R Plante wrote:

DAP wrote:

devotEE wrote:

In this device the charge is stored on the electrodes.

EEventually wrote:

…The field remains because of the charge on the plates. We call them insulators because they don't move charges.

I respectfully disagree. If Eestor wanted to make their PET/coated-CMBT composite as insulating as possible (therefore ensuring that charge remains on the aluminum plates), they would have never poled it.

See Analysis of electric conduction mechanisms in polyethylene terephthalate. In particular, see Fig. 1 which shows that the repeated cycling of applied high voltage increases the current observed when applying that voltage in later cycles.

I agree more with the following sentiment: http://www.theeestory.com/posts/117061.



Dan, I read the paper and I don't see what you're referring to. The paper basically profiles a very good insulating material, made even better by poling that produces bi-polar space charges. This is basically an electret, and the reduction in leakage current due to the space charges in electrets (in plastics as well as ceramics like alumina) is well documented in the literature.

From figure 1, the leakage current at 1.5 V/um is extraordinarily low at aprox 1.5 pA/cm2 on their 6cm diameter sample (gee, I wonder how they measured 45pA ;)

Even at 20 V/um it's only about 1.5 nA/cm2. The difference between the poled measure of 175 pA and the unpoled measure of 45pA might seem relatively large, but in absolute terms they are equally tiny.

I also don't see any attempt by them to find a space charge saturation point by leaving their moderate (not high) fields applied for a considerable time (minutes to days). If they did they might have noticed an eventual drop in leakage current, or a flattening of the curve with higher applied fields. That was not the focus of their experiment though.
DAP,

In the research paper there seems to be no indication of what units they are using in their graphs of current - is it amps for the whole specimen, amps per square metre, or amps per square cm?

In the absence of any indication perhaps they should be interpreted as current through the specimen.

Since the electrodes extend only over a 5cm diameter, then it is better to use this rather than a 6cm diameter as current cannot flow through an area of specimen without electrodes. So the area through which the current flows is pi x 52 / 4 (to square the radius not the diamter) = 19.6 cm2. Call it 20 cm2 to make all the maths easier. Since there are 10,000 cm2 in a square metre then we must multiply current figures by 500 to get A/m2.

If you assume ohmic behaviour, then around 3 x 10-7 amps for the specimen at 180 volts for 10 um thickness requires we multiply by 500 (for area) and 20 (for voltage compared with 3,600V). The current would then become around 3 x 10-3 A/m2 = 3mA/m2. Since the EESU has 60 coulombs per square metre of charge then at the full voltage 60 C would flow in 60/0.003 seconds = 20,000 seconds or 6 hours through the PET.

Then we have to take into account that the PET represents only say 4%, which increases the time up to 150 hours, or getting on for a week to mostly discharge.

Hopefully DW's PET is much much better than the stuff measured in this paper, or the current measurments are amps per m2 or something . Otherwise the EESU is dead in the water!

So it is easy to see why you might be concerned!!

If the currents are in A/m2 then we can kick off by multiplying by 500, so the discharge times then become around 500 weeks or approximately 10 years, which is more in line with the EESU patent, though not quite as good. That's not the whole story though, as Poole-Frenkel currents rise exponentially with the square root of the voltage rather than linearly.

I've emailed Eugen Neagu to ask for clarification on the scaling of the currents in the graphs.

Regards,
Peter



Pete, the authours did provide the requisite data to derive that mathematically. I already derived it. You even quoted my derivation above.

PS - Poole-Frenkel is square root of field, not voltage.


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Thu, 05 Jan 2012, 3:48am #82
SimonB
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ee-tom wrote:

BT is 0.44 J/(gK)

it varies a bit with phase, and has a small peak at the FE/PE transition.

Best wishes, Tom

Thanks Tom, I hoped someone would have the definitive value.
Simon


"nanotechnology is going to be huge" (Lord Sainsbury).

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Thu, 05 Jan 2012, 4:59am #83
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Daniel R Plante wrote:

Technopete wrote:

Daniel R Plante wrote:

DAP wrote:

devotEE wrote:

In this device the charge is stored on the electrodes.

EEventually wrote:

…The field remains because of the charge on the plates. We call them insulators because they don't move charges.

I respectfully disagree. If Eestor wanted to make their PET/coated-CMBT composite as insulating as possible (therefore ensuring that charge remains on the aluminum plates), they would have never poled it.

See Analysis of electric conduction mechanisms in polyethylene terephthalate. In particular, see Fig. 1 which shows that the repeated cycling of applied high voltage increases the current observed when applying that voltage in later cycles.

I agree more with the following sentiment: http://www.theeestory.com/posts/117061.



Dan, I read the paper and I don't see what you're referring to. The paper basically profiles a very good insulating material, made even better by poling that produces bi-polar space charges. This is basically an electret, and the reduction in leakage current due to the space charges in electrets (in plastics as well as ceramics like alumina) is well documented in the literature.

From figure 1, the leakage current at 1.5 V/um is extraordinarily low at aprox 1.5 pA/cm2 on their 6cm diameter sample (gee, I wonder how they measured 45pA ;)

Even at 20 V/um it's only about 1.5 nA/cm2. The difference between the poled measure of 175 pA and the unpoled measure of 45pA might seem relatively large, but in absolute terms they are equally tiny.

I also don't see any attempt by them to find a space charge saturation point by leaving their moderate (not high) fields applied for a considerable time (minutes to days). If they did they might have noticed an eventual drop in leakage current, or a flattening of the curve with higher applied fields. That was not the focus of their experiment though.
DAP,

In the research paper there seems to be no indication of what units they are using in their graphs of current - is it amps for the whole specimen, amps per square metre, or amps per square cm?

In the absence of any indication perhaps they should be interpreted as current through the specimen.

Since the electrodes extend only over a 5cm diameter, then it is better to use this rather than a 6cm diameter as current cannot flow through an area of specimen without electrodes. So the area through which the current flows is pi x 52 / 4 (to square the radius not the diamter) = 19.6 cm2. Call it 20 cm2 to make all the maths easier. Since there are 10,000 cm2 in a square metre then we must multiply current figures by 500 to get A/m2.

If you assume ohmic behaviour, then around 3 x 10-7 amps for the specimen at 180 volts for 10 um thickness requires we multiply by 500 (for area) and 20 (for voltage compared with 3,600V). The current would then become around 3 x 10-3 A/m2 = 3mA/m2. Since the EESU has 60 coulombs per square metre of charge then at the full voltage 60 C would flow in 60/0.003 seconds = 20,000 seconds or 6 hours through the PET.

Then we have to take into account that the PET represents only say 4%, which increases the time up to 150 hours, or getting on for a week to mostly discharge.

Hopefully DW's PET is much much better than the stuff measured in this paper, or the current measurments are amps per m2 or something . Otherwise the EESU is dead in the water!

So it is easy to see why you might be concerned!!

If the currents are in A/m2 then we can kick off by multiplying by 500, so the discharge times then become around 500 weeks or approximately 10 years, which is more in line with the EESU patent, though not quite as good. That's not the whole story though, as Poole-Frenkel currents rise exponentially with the square root of the voltage rather than linearly.

I've emailed Eugen Neagu to ask for clarification on the scaling of the currents in the graphs.

Regards,
Peter



Pete, the authours did provide the requisite data to derive that mathematically. I already derived it. You even quoted my derivation above.


PS - Poole-Frenkel is square root of field, not voltage.

You might be right Dan, but I could not see it. I checked the text on the images, read the thing multiple times and used PDF search to look for capital A, amps and current.

Normally you would expect to quote current in terms of current density to make things easier for your reader, but they may not have done this.

So help me out in case Eugen Neagu does not reply - where in the paper do they specifically give any scaling for the units for the graphs? They do quote current density in one of the formulae, but not elsewhere.

Most likely the graphs are in terms of current through the specimen, as you assumed. But the extrapolation of the upper point of figure 1 causes with this assumption gives a much higher value for leakage than would be tolerable.

DAP may be right in that traps will reduce this, but it has to do so by something like a factor of 500 before you get down to the 2008 patent leakage figures.


PS - Poole-Frenkel is square root of field, not voltage.
Yes it is and you and I both know that, but when you are dealing with a specimen of known thickness (10um) which conveniently is the same thickness as PET surrounds in the EESU then the relative factors are also the same function of voltage across the sample, as this bears a fixed relationship to the electric field.

And yes, I take a lot of short cuts when working stuff out, because, like most physicists, I am unwilling to do unnecessary work.

Regards,
Peter

Last edited Thu, 05 Jan 2012, 8:41am by Technopete


Assumptions: 1) E=1/2CV2. (Only dummies assume this). (I am one of these dummies).

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Thu, 05 Jan 2012, 8:55am #84
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Technopete wrote:

The point of this is that it is this leakage current that is the conduction of charge which you believe will create electrets in the PET during poling. So if the leakage current is miniscule, then PET electrets will be rare and can only cause minimal leakage after poling.

Actually, that is not the point I’m trying to make. My original point in Post # 42 was simply that poled PET would be 'leakier' than PET that had not been poled. I don’t believe, however, the data in Analysis of electric conduction mechanisms in polyethylene terephthalate will be helpful in determining how much leakage can be expected when PET (previously poled at 180oC and 2000V) is continuously subjected to 3500V. First, PET poled in this manner will develop deep-level traps (unlike the material in this reference). Second, 3500V is much greater than the voltage used to obtain the data in this reference. More about this below.

Daniel R Plante wrote:

Dan, this process is for the most part, dependant on material temperature and is profoundly self-extinguishing and extraordinarily fleeting. It is inevitable in intrinsic semiconductor material, and insulators as well. This is not conduction band charge carrier availability nor valence band charge carrier availability. The physical explanation for this distinction is beyond the scope of a blog post.

I agree that electrical conduction in insulating polymers can be very dependent on temperature. It is also dependent on impurities (such as charge traps), voltage, and frequency (should the voltage not be a constant DC). As far as charge transport in insulators or semiconductors that contain deep-level traps being profoundly self-extinguishing and extraordinarily fleeting – I’d appreciate a reference pointing out how this is so, especially since the explanation is beyond the scope of a blog post. Additionally, I offer up a reference that counters your assertion. From the introduction of A New Ultra Fast Conduction Mechanism in Insulation Polymer Nanocomposites
Insulating polymers are a category of organic materials widely used in electrical apparatus, exhibiting low charge carrier concentration and mobility (usually 10-16– 10-14 m2V-1 s-1), thus low electrical conductivity, even at high fields [1]. Carriers in insulating polymers are introduced by impurities and contaminants, as well as by charges injected from the electrode-insulation interface. When the electrical field applied to the polymer is higher than the threshold for space charge accumulation, charge would be injected into the bulk material from the interface of polymer-electrode and accumulate, forming homocharge or heterocharge. Based on this traditional conduction mechanism, the current is a continuous flow of carriers, which gradually approaches a steady state value at a given time after the onset of voltage application. [emphasis added]

It occurs to me that should the aluminum plates maintain a continuous 3500V, the electric field applied to PET would be higher than the threshold for space charge accumulation, thereby leading to a continuous flow of carriers at steady state.

Going beyond the introduction, however, this paper shows how inclusion of particulate matter into a polymer matrix can dramatically alter charge transport. I believe it wise to keep in mind that Eestor is using a pulsed DC process in order to energize their dielectric. Accordingly, this paper may also give us a glimpse of what may be happening as far as energy transport from the aluminum plates to the dielectric is concerned.

Finally, from 06Nov09:

Schneibster wrote:

Right now today, we do not know how Colossal MagnetoResistance (CMR) works. Nobody has a model of it. We know it's there because we can measure it. The closest they can come is to say, well, we know there're some polarons in there, and when we try to model what happens to them we seem to see them liquifying and then resolidifying. The problem with this, of course, is that polarons have no more real an existence than solitons; they have a real part, the charged particle, and an imaginary part, the part that stresses the lattice around them. What it means to say this "liquified" is pretty dicey. Sure as hell looks like waffling to me; I'm betting it'll turn out to be a phonon cloud- just the series of distortions- plus the charge.

Please stop telling me we know how everything works. We don't.

[link to ‘soliton’ added]

I’d like to turn Schneibster’s final sentence around a bit. I think we should be very careful drawing conclusions from experiments run on systems that do not closely match what Eestor has described and think that they tell us how components of the Eestor dielectric will work. They won’t.

Last edited Thu, 05 Jan 2012, 9:54am by DAP


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Fri, 06 Jan 2012, 8:32am #85
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From http://www.theeestory.com/posts/97409 (31Dec09)

ee-tom wrote:

nekote wrote:

ee-tom wrote:

... We DONT need to know the magnetic field (if static), ...
Given the spin waves (magnetic waves) I've just been introduced to, what if the magnetic field is *NOT* static?

Lovely wiggly Java applet animation:
http://www.angelfire.com/wa/hurben/swaves.html
Repeated single clicks can increase or decrease H (what ever field that is).
Also, the tip of the "blue" arrow can be dragged in the first quadrant area to change both angle and length of 'k' vector.

Certainly a "whole lotta' shakin', goin' on", to quote an Elvis Presley song.

Unfortunately, I don't have a good clue, yet, if it could be significant, or not. :(

Magnetic fields varying fast enough to make significant changes to electric fields via indiced voltages are totally out of court. They lose energy through eddy currents and radiation. But in any case I don't think anyone would seriously imagine energy storage via rapidly changing magnetic fields.

Sorry.

From the conclusion of Excitation of spin waves by a spin polarized current:

In our work we succeeded in establishing that there are four possible spin wave excitation regimes in the presence of an applied spin polarized current. Depending on the magnitude of the current we can have:

a. A damped regime where the system approaches a new static equilibrium.

b. A steady-state regime, characterized by a nearly constant excitation of a very few low frequency modes, and relatively small excitation of other modes.

c. Oscillatory behavior, where a broad spectrum of modes is excited, with the preference given to low frequency modes.

d. Switching, where the semi-steady state excitation of modes is superseded by very fast damping into the new static equilibrium, with the magnetization anti-parallel to its initial value.

It turns out that spin waves (and the spin torque energy associated with them) can be confined such that they are near lossless. Then again, if there is an ordered array of spin waves, they can all work together. See Ferromagnetic nanodisks for magnonic crystals and waveguides.

Edit: A recent review article of interest - The building blocks of magnonics.

Edit: Another review of interest - Nanostructured Metamaterials

Last edited Sun, 08 Jan 2012, 9:06am by DAP


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Fri, 06 Jan 2012, 12:47pm #86
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From The building blocks of magnonics:

The idea of the spin-wave based computing concept to parallelize computation uses a reconfigurable mesh architecture. Spin-wave guides transmit the signal at each line. The chip consists of a mesh of N x N spin-wave switches interconnected by ferromagnetic spin-wave guides. Each node is realized by a ferromagnetic switch. If the switch is “on”, the spin wave is guided into the crossed line to the spin-wave buses output. The switching frequency is in the order of GHz and transmission speed is 104ms-1, allowing fast data processing. In the architecture presented in Refs. [6, 7], excitation is realized by a strip-line; detection will be realized by inductive detection at a second strip-line. The spin-wave switch at each crossing could be realized by a diluted magnetic semiconductor which can be switched from a ferromagnetic to a paramagnetic state by applying positive or negative voltages. It should be remarked that as of today, this concept is lacking a realistic practical implementation. Ferromagnetic semiconductors like Mn-doped GaAs have both a very strong spin-orbit interaction and a critical temperature that is below room temperature, and hence will not work for actual devices. [emphasis added]

A new use for CMBT? (CMBT is a diluted magnetic semiconductor - critical temperature unknown)

Last edited Fri, 06 Jan 2012, 12:56pm by DAP


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