Focus Fusion news story

[ladajo]

Yup.

[chrismb]

lolololololololol chrismb arguing with joe, I think I can die happy now.

There are no responses from chrismb to the other party.

No argument is possible with the other party, only contradiction.

'Contradiction' is not 'argument' (...even if, no doubt, the forum will soon be instructed it is the same word in Khazak).

***Insert here link to classic 'Monty Python' sketch on the subject***

The other party has reduced any rational discussions on this forum to a complete Pythonesque joke.

[Joseph Chikva]

Temperature is measured in eV. Don't matter if the distribution is Boltzman or monoenergetic.

Mass also can be expressed in eV. Without irony - "wrong forever"

I see you have discovered the secret of the universe mass = energy.

I did like your "also" can I consider that progress?

rest mass of electron me=511 keV
rest mass of proton mp=938 MeV
and so on.
Best regards,

[Robthebob]

I guess a quick summery of the recent development.

-2 to 3 more years before we know for sure, which is very annoying, given that last year, we should've gotten an answer, back then it was delayed to about 5 months ago, now it's 2 to 3 years more... a little bit annoying, hopefully no carrot on stick.

-High beta has been done, high beta on high field should have been done, given they built a bigger electron gun 4th quarter 2011; 1st quarter 2012 should've been, as stated by the progress report, for testing high beta on high fields.

-Implications that WB effect is happening, because a bigger electron gun=better heating. According to the recent J&A, the gun is to shoot more electrons into the system, thus trying to get to high beta. Consider if you get to high beta and no WB effect, then that would be a wrap for the machine. More electron=high beta at high fields=?WB effect=better performance=better heating.

-Some people around here are saying the panel review in the recent J&A is for the most recent reward (at least way more recent than the panel review for the first contract after emc2 released a bunch of stuff to the public, went to google, etc) So this is suggesting that there's been 2 reviews, 1 for the first contract, 1 for a recent reward; i may have read wrong, but was this explicitly stated in the J&A? The review mentioned in the J&A says good things about polywell, so thumbs up. Although it would be a lot more trivial if that panel review was just the first one to get the first contract, and there's no second review.

-USydney.... Dont know what they're doing, they published another paper a while back, hopefully I can go to grad school there.

-Some say the 5 years mentioned in the J&A, which is for "production", would be a mark after they're done with the demo plant (I think), I dont know what production means. So high estimate, as in 5 years means in 5 years they'll be done with all experiments, ready to finish designing and build a demo plant, would be maybe 3 more years on top of that? So 8 years? Low estimate would be 5 years, we know for a fact possibly in 2 or 3 years, they're done building demo plant in 5 years. Just speculations.

[Joseph Chikva]

Temperature is measured in eV. Don't matter if the distribution is Boltzman or monoenergetic.

Rhetoric question

Theoretical considerations of the emittance value, given by ion temperature and aberrations of the extraction system, allows an estimation of the emittance of a 170 mA at 55 keV proton beam.

What is ion temperature there? 55keV or about 1-2 eV?

[Skipjack]

So it seems daft in the extreme for anyone to argue that Polywell will obviously not work given our relative uncertainty and the known at least conditionally positive view of people who have:
(a) more information
(b) more expertise
than us.

Ohhh, I totally agree with that!

[MSimon]

1eV = 11,604.5 deg K

[Joseph Chikva]

1eV = 11,604.5 deg K

And what temperature that beam has? 11'604-23'208 K (1-2 eV) or 638'220'000 K (55 keV)

For your reference that (1eV = 11,604.5 deg K) is only simplification. And energy is not temperature. As in e.g. SI system unit of energy is not K but J.

[D Tibbets]

My two cents worth (or would that be pennys, rubles,...) This discussion of units of measure being used as a arbiter of physics or innapropriate communication is self defeating. The temperature can be described in various ways depending of the state of the matter, the field of study, etc. The only constant I know of temperature is that it involves the average kinetic energy of a substance or sysatem, and even this may be local. eV on the other hand may describe a more limited subset of a system. Unless you use a qualifier like the Average eV of a population. Accept that temperature = average eV times a constant. Except when temperature is used for a single element, when the average would not apply as you are applying the term to a single entity. anything further is an argument about language and jargon, not about physics.

Even using eV as a measure of mass can be confusing. Certainly you can say that it takes ~500,000 eV worth of energy to create jmkan electron. Collisions of particles with mass can do this if their center of mass merging KE equals this. But what if it is laser light providing the energy. Can you use the same definitions when the photons involved have zero mass? You have to throw in qualifiers like E=mc^2, etc. Things get more complicated.

Use the terms that seem reasonable, don't use the units as a weapon but as a tool for admittedly less than perfect communication.

If you wish to have an example of miss communication of scientific terminology and it's consequences look no further than a particular Mars probe. This is not a fault of measurement or calculation but of mixing of units without careful compensation.

Dan Tibbets

[Joseph Chikva]

The temperature can be described in various ways depending of the state of the matter, the field of study, etc.

First of all "temperature" is a measure of average kinetic energy of particles of thermal system. And not measure of coherent.
Why I asked MSimon that question?
Because actually in that example 55 keV beam has a temperature not more than temperature of “cold” plasma (1-2 eV) from where those protons were extracted before acceleration.

[Robthebob]

It really depends on what you mean, according to my stat mech book:

(1/T)= (dS/dU) Holding N and V constant. More irrelevant information coming right up.

MSimon is correct tho. Let me show you the math,

1eV=1.6022 x 10^(-19) J

k(b)=1.380650 x 10^(-23) J/K

So 1eV/k(b)= 1.160 x 10^(4) K

The famous Ideal Gas Law relates energy to temperature, just as Einstein's energy mass law relates energy to mass. Not that any of that matters, because here we are, arguing about very established things, again suggesting you're either stupid or a troll. I suppose what chrismb said about banning someone that posts nothing but none sense is not a bad idea. MSimon is a huge proponent of free speech though.

But it's all good, you're Joe, you're always right, and I'm sure you're still right even now.

PS: I do admire your works of art, it must take some considerable amount of effort to make your posts as good as they are.

[Joseph Chikva]

according to my stat mech book:

don't pull out from a context, Mr. forthcoming plasma physicist
Term "temperature" does not make sense for non-thermal systems.
And 1 eV = 11600 K is relevant to only thermal

I am asking once again:
What temperature has 55 keV beam from that example?

Theoretical considerations of the emittance value, given by ion temperature and aberrations of the extraction system, allows an estimation of the emittance of a 170 mA at 55 keV proton beam.

[Joseph Chikva]

(1/T)= (dS/dU) Holding N and V constant. More irrelevant information coming right up.

MSimon is correct tho. Let me show you the math,

1eV=1.6022 x 10^(-19) J

k(b)=1.380650 x 10^(-23) J/K

So 1eV/k(b)= 1.160 x 10^(4) K

The Boltzmann constant, k, is a bridge between macroscopic and microscopic physics, since temperature (T) makes sense only in the macroscopic world, while the quantity kT gives a quantity of energy which is on the order of the average energy of a given atom in a substance with a temperature T.

Now if temperature (T) makes sense only in the macroscopic world let's define what is 1 eV

By definition, it is the amount of energy gained by the charge of a single electron moved across an electric potential difference of one volt.

So, if single electron moves across an electric potential difference of one volt that gains the 1 eV
Does for that electron "temperature" make sense? The same is correct for all accelerators. But MSimon speaks about "heating" of beams instead of "acceleration.

[tomclarke]

(1/T)= (dS/dU) Holding N and V constant. More irrelevant information coming right up.

MSimon is correct tho. Let me show you the math,

1eV=1.6022 x 10^(-19) J

k(b)=1.380650 x 10^(-23) J/K

So 1eV/k(b)= 1.160 x 10^(4) K

The Boltzmann constant, k, is a bridge between macroscopic and microscopic physics, since temperature (T) makes sense only in the macroscopic world, while the quantity kT gives a quantity of energy which is on the order of the average energy of a given atom in a substance with a temperature T.

Now if temperature (T) makes sense only in the macroscopic world let's define what is 1 eV

By definition, it is the amount of energy gained by the charge of a single electron moved across an electric potential difference of one volt.

So, if single electron moves across an electric potential difference of one volt that gains the 1 eV
Does for that electron "temperature" make sense? The same is correct for all accelerators. But MSimon speaks about "heating" of beams instead of "acceleration.

Joseph,

Others as above have explained at top level. But you obviously want more detail. So here goes. It is common sense + physics.

It is true that technically the temperature of a coherent mono-energetic high energy beam can be low (and, more technically, relativity shows that mono-energetic beams are at some level equivalent to stationary particles).

However if you consider the practical interactions of such a beam with another system you can easily work out the effective temperature.

So: take an equilibrium plasma or gas enclosed in perfect reflective walls with temperature T0. Assume for simplicity we have only a single species of N particles, average energy E0. We know that:
E0 = kT0.

Add a monoergetic coherent beam (for simplicity of the same particles) of energy E1/particle. The beam consists of M particles (so we can be quantitative).

Assume that after some time the system equilibrates to a Boltzmann KE distribution.

Conservation of energy within the box tells you, trivially, that the temperature of the box is now (E0N+E1M)/(N+M).

From which we derive an effective temperature for the monoenergetic beam (in this context) of T1 = E1/k as everyone here except ypou would expect.

In reality this effective temperature comes from increase in entropy in the mono-energetic beam energy as this passes to the (high entropy) system.

It is technically an abuse of notation to talk of a high-energy particle beam as having a temperature related to its particle energy but you can see that it makes good sense, and explains how such a beam can heat a gas or plasma providing its particle energy is higher than the gas particle energy. All of which is accepted by people who talk about such things.

Now, I am all for looking one level deeper and noting that a coherent beam in fact technically has a low temperature. But only if you also note that its effect when coupled thermodynamically to an equilibrium particle distribution is that of a high temperature source because of its low entropy and embodied energy.

What we want to do, when reasoning about these systems, is to have a good intuitive understanding of what is going on. That can be at any level of approximation. But viewing a high energy coherent beam as having low temperature, without a lot of extra work, satisfies none of these levels of approximation and is plainly stupid.

MSimon (and others here who are engineers) will I am sure bear this out: maths is the most important tool when analysing complex systems. You can't do anything without it. But understanding systems requires not just the blind application of math equations, but realising what they mean in specific contexts so you use appropriate approximations. That is a lot more difficult than just learning math. But also more fun.

Now - back to topic. Why not admit that the ONR commisioned panels who have reviewed Polywell science have the expertise and data to give it the thumbs down if it were obviously daft? So if you think this you need to reexamine your own assumptions.

EDIT - gas thermodynamics is not what I usually work with. So others will correct any errors in the above I am sure.

[Robthebob]

gonna go ask someone first about this.