FAQ - Temperature!...of a fusor...of fusion

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Richard Hull
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FAQ - Temperature!...of a fusor...of fusion

Post by Richard Hull » Mon Mar 10, 2014 6:07 pm

Outside and inside "REAL temperatures:
There is an atmospheric temperature of the fusor shell and it will rarely reach the boiling point of water. There are localized spot high temperature zones where ion and electron streamlines impact the walls. These spots are much warmer. They are the source of spot heating of the shell which, over operational time, contribute to the overall outside, atmospheric temperature of the fusor shell. These spot heating points might reach 500 deg C at the impact point inside a fusor which is a very tiny point. In glass bell jars, this is a point of great danger and can lead to flaking of localize glass chips and, if continued, could result in total failure of the jar and a dangerous implosion.

All metal fusors are in no danger of overheating unless the use of very soft soldered or epoxied joints are part of its construction. All joints should be TIG welded or Hard silver soldered (brazed). A fusor can be cooled if desired by winding a coil of copper tubing over the fusor body and pumping water through the tubing to a heat exchanger and recirculated. I think only one or two of our folks have attempted this. Thus, it is not necessary to cool the average fusor.

Fusion temperatures:
There are temperatures or more honestly, energies, often quoted in degrees kelvin related to the internal fusing plasmas. The use of the word "Kelvins" is proper, but few folks detail this fact. In these often misleading statements, mostly giving by physicists trying to impress a lay audience, millions of degrees are quoted. They often never add the word kelvins. Why confuse the ingnorant with the proper terminology? Just say it in degrees like the temperature they understand in day to day life. (deliberately misleading)

The fusor's internal "ion" and fusion temperatures in kelvins are in a vast range. From as cool as a low of 165,000 degrees to the ideal fusion ion-ion collisions resulting in fusion of 440 million degrees in a 40 kilovolt fusor (my fusor IV). Most of the ions in a 40kv, (440million degree), fusor are much hotter than 1 million degrees and much cooler than 100 million degrees. I have delivered the foregoing as a fusion physicist would deliver it to the media when talking about how close they are to doing fusion. Again, substitute the word "Kelvins" in every instance where I used degrees and the truth is told.

The fusor fuses in "velocity space" and not in a unifrom plasma as in a thermal fusion machine (tokamak, ITER). This is key to its operation. We are dealing with ion-ion, ion-neutral and neutral-neutral collisions when we fuse in an IECF fusor within velocity space, thus, there is a range of energies within velocity space.

The fusion in a fusor or a tokamak occurs in a hyper-thin atmosphere of deuterium ions and not a "feelable" solid, so, a "feelable" heat in kelvins or degrees is just not there. Temperature, (thermally speaking), is nothing more that the speed of particles in a solid, liquid or gas and nothing more. The faster those particles move, the higher the temperature in kelvins or degrees of that particle. In solids, quintillions of particles all colliding with each other, make a "feelable" temperature to our skin. In a vacuum level gas of fusing deuerium all gas particles that are moving about at a relative temperature of 100 million kelvins would feel incredibly cold.

In deep space the temperature is near absolute zero degrees and zero kelvins. Why? There are only a rare few particles moving about per square cm. In space your hand, a solid, would rapidly freeze due to the moisture in your body....YET.... the few particles impacting your hand's skin in space each second are at millions or even billions of kelvin degrees, (cosmic ray matter particles, etc.)

* note * There is some amount of beam on target collision in the fusor that does not involve velocity space fusion. (explained in another FAQ)

Fusion temperatures are conversions of the energy of the deuterons and neutrals in motion, (kinetic energy), to an equivalent temperature of a particle in motion in a sea of molecules in a solid substance at that temperature. In the fusors or any fusion device, you are in a "near space" vacuum of flying deuterons and neutrals and not in a solid, so, you can't relate this to a "feelable", "touchable", temperature that our senses are commonly linked to. The normal method of talking amongst fellow physicists would be to discuss the energies as "electron volts" (ev). The relation of electron volts to kelvins is to multiply the (ev) kinetic energy of the particle by about 11,000. A 1kev particle is said to represent an 11 million kelvins particle. (11 million kelvin degree particle in botched speak)

The general public would have issues understanding this concept and the fusion physicist absolutely relies on this to befudle and confound.
Don't be a "general public" type! If you are still confused, read up on the physics and Boltzmann's work on thermodynamics.

Absolute zero = no motion of any particle = -273deg C = - 460 deg F = 0 kelvins = 0 eV (electron volts)
Water freezes at 0 deg C 32 deg F .0235 eV (corrected by Joe Ballentyne - Thanks)

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: Temperature!...of a fusor...of fusion

Post by Jeroen Vriesman » Wed Mar 12, 2014 10:01 am

Translating the speed of accelerated particles to temperature seems a bit confusing to me.

Temperature is defined for a system in "its own state of internal thermal equilibrium", which usually implies a maxwellian speed distribution.

On the other hand, a beam of high speed particles, where all the particles have the same speed can be called "cold", in the right frame of reference it can have a very low temperature while real temperature does not depend on the frame of reference (I think there are still some mysteries about relativistic transformation of temperatures, but that's another discussion)

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Re: Temperature!...of a fusor...of fusion

Post by Richard Hull » Wed Mar 12, 2014 4:05 pm

........"Temperature is defined for a system in "its own state of internal thermal equilibrium", which usually implies a maxwellian speed distribution"......

This is why the "maxwellian tail", that I have noted before is where most fusion occurs and is, therefore, no place to hang your fusion hopes and dreams.

This FAQ was more of a way to link the concept of temperature claims of the press quoting from a physicist who is boosting his own fusion efforts to the reality of what temperature means in our normal day-to-day sense of temperature. It also sought to define the electron volt concept of particle kinetic energy to Boltzman's thermal particle kinetic motion. Boltzman is the guy to blame for setting up the conversion, but the phsyicist is the one to blame for dealing the lay person the jargon of "hundreds of millions of degrees in a 10kev plasma.

We have a lot of regular folks and younger fusion aspirants showing up here who have not been exposed to the physics of fusion to any great depth, but who have been enthralled by the terms of "hundreds of millions of degrees" needed to do fusion.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: FAQ - Temperature!...of a fusor...of fusion

Post by JoeBallantyne » Tue Nov 10, 2015 1:28 am

One correction to the FAQ above: Water freezes at 32 deg F = 0 deg C = 273 K = 0.0235 eV.

Editor's note: Dan, Thanks for finding my faux pas. I have edited the original posting and credited you with the correct value.
RH

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Re: FAQ - Temperature!...of a fusor...of fusion

Post by Dan Tibbets » Tue Nov 10, 2015 5:08 am

I don't think expressing temperature in what ever common unit of measure is terribly miss leading. Mildly miss leading perhaps, but close enough for general discussions. 1 million degrees C equals 1,000,273 degrees K. Not much relative difference. Degrees F would be ~ 9/5ths greater, but this is still only 1,800,304 degrees F (if I calculated right). Close enough for most general discussions. Well almost, C is very close, and F may require an appreciation that a factor of almost two may need to be remembered.

As for the temperature of the cosmos. It has little to do with the KE of any very rare particle that may hit and transfer +/- heat to a test object. The average density of particles is just to small to contribute much. The cosmic background radiation temperature refers to the wavelength of light that that would be emmited via theoretical black body radiation. I think it is primarily a consequence of the expansion of the universe acting on the average temperature of the universal gas once it became transparent to radiation. It ties in with the red shift of galaxies that is used to measure distance/ time.

I'm not sure how quickly you would freeze if exposed to the vacuum of deep space. Unless you were undergoing evaporative cooling, the only way of getting heat away from your body would be radiation. There would be no convection or conduction of heat. There is a moderate temperature difference (~ 300 degrees C or K). Compare this to a heat light where the temperature difference may be twice that. Of course exposed surface area and other considerations apply. The cold of deep space does have significant effects, just not as much strength(rapidity) as other methods of heat transfer under common human environments. I suspect your body temperature would drop more rapidly if you fell off of the Titanic into the North Atlantic (at least till you closely approached the temperature of the water). Without a space suit, you would very quickly lose consciousness with death closely following due to suffocation. Your blood may boil- at least in areas close to the surface, things may rupture or become engorged with blood- like the lungs. Freezing would be a more gradual process. This is not to imply that the cold temperature of deep space is completely trivial. Frost/ dew forms in open fields at night faster than under trees due to radiative cooling to deep space. This despite any convection processes that tends to even out the temperatures provided there is little wind (enhanced convection processes).

Dan Tibbets

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