How LPPX could overcome the Dynamical neutron saturation?

[Francisl]

An alternate power formula is P=(E^2)/R. A little increase in voltage or a little decrease in resistance makes a big difference.

[MTd2]

Aeronaut wrote: Long distance transmission lines double the voltage to reduce the current by 50%. Using P=(I^2) R, doubling the transmission voltage results in 25% of the losses. Not sure how this relates to raising voltage to raise current…

There are 2 things here. The wasted energy in collisions and the free electrons. The wasted energy will go like P=(I^2)*R anyway, like in a wire. This is a fraction of the electrons that effectively behave like they were in a resistive medium.The increase of I of an input just makes things go even more wasted.

But note that “P” is not the total energy of the capacitor banks, just the part where it is wasted. So, by increasing the total voltage AND keeping BOTH total resistance (which would happen naturally anyway) and total current CONSTANT, is the same as diminishing the current that goes through the resistive process. So, not only R goes down, as also I (resistive) go down so that conservation of energy is respected. So, more current will be available to be absorbed by the pinch.

[vansig]

MTd2 wrote:

Long distance transmission lines double the voltage to reduce the current by 50%. Using P=(I^2) R, doubling the transmission voltage results in 25% of the losses. Not sure how this relates to raising voltage to raise current…

There are 2 things here. The wasted energy in collisions and the free electrons. The wasted energy will go like P=(I^2)*R anyway, like in a wire. This is a fraction of the electrons that effectively behave like they were in a resistive medium.The increase of I of an input just makes things go even more wasted.

But note that “P” is not the total energy of the capacitor banks, just the part where it is wasted. So, by increasing the total voltage AND keeping BOTH total resistance (which would happen naturally anyway) and total current CONSTANT, is the same as diminishing the current that goes through the resistive process. So, not only R goes down, as also I (resistive) go down so that conservation of energy is respected. So, more current will be available to be absorbed by the pinch.

So, what are the quantitative predictions around this?
do you think the voltage will have to be raised to, say, 75kV?
lower? higher?

[MTd2]

The papers are just about the interval up to 50KV, and this is clearly not enough since the LPPX is 45Kv. 90KV is clearly the ideal, but I don`t know the lower value. I`d have to play with the values and I`d have to play with the simulation spreadsheet first. Let me make an estimative though. Saturation occurs when all wasted energy is due the dynamical resistance. So, that means an asymptotic value of V=RI. For an optimized configuration of 100KV, see table 3, ( https://focusfusion.org/index.php/forums/viewreply/7483/ ) is about 1.5MA, we achieve a pinch saturation at 1.5MA @ 35KV. Given that we want saturation to occur at 3MA, we must double the voltage, to 70KV. Give a bit of safety margin, to avoid the flatten curve before saturation, we could say 75KV. So yes, your guess is right.

[Francisl]

I have an odd question. If 45 KV is not high enough, can we use a 30 to 50 KV deuterium particle beam to bombard a 45 KV pinch? Would that provide the 75 to 95 KV energy to probe the voltage levels that would be effective?

[MTd2]

Francisl wrote: If 45 KV is not high enough, can we use a 30 to 50 KV deuterium particle beam to bombard a 45 KV pinch? Would that provide the 75 to 95 KV energy to probe the voltage levels that would be effective?

Not really, because what causes the fusion is the dense current of the pinch.

[MTd2]

There is a DPF device that has parameters much larger than LPPX:

(4.1mF, 300kV, 4MA, 187kJ, 400ns time to peak current, dI/dt ~ 1013 A/s)

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332004000800054

Speed 2, at Leopoldo Soto lab, one of the friends of LPPX, I think.

There could be some sort of collaboration. I guess they can achieve a few thousand of Joules with their Speed 2, in case LPPX doesn`t succeed. At least, the quantum suppression of bremsstrahlung could be demonstrated.

[Francisl]

MTd2 wrote:

If 45 KV is not high enough, can we use a 30 to 50 KV deuterium particle beam to bombard a 45 KV pinch? Would that provide the 75 to 95 KV energy to probe the voltage levels that would be effective?

Not really, because what causes the fusion is the dense current of the pinch.
Looks like it has already been tried with an electron beam: Neutron enhancement

[MTd2]

I cannot read that paper but to achieve relativistic speeds would be necessary way too much energy, even to set up the EM potential of the electrodes, which would be enormous.

[vansig]

MTd2 wrote: …
Summing up, not even with Poseidon, which has banks of 750KJ and a voltage of 80KV, were capable of achieving more than 1.5MA of current in the pinch. This is real bad since it means a neutron yield one magnitude lower than what is desired for LPPX for an equipment with much higher capacity.

by the way,
the forum software, here, mangles URLs that embed spaces or punctuation, but you can use a shortener:

http://www.plasmafocus.net/IPFS/Papers/PP1Published APPLAB922021503_1witherratum.pdf
–> http://tinyurl.com/2uho7a9

http://www.intimal.edu.my/school/fas/UFLF/Papers/PP3PublishedPPCF 50 (2008) 065012 .pdf
–> http://tinyurl.com/38u9lfd

http://www.plasmafocus.net/IPFS/2010 Papers/Energies PP.pdf
–> http://tinyurl.com/346zl96

[zapkitty]

vansig wrote:
by the way,
the forum software, here, mangles URLs that embed spaces or punctuation, but you can use a shortener:

http://www.plasmafocus.net/IPFS/Papers/PP1Published APPLAB922021503_1witherratum.pdf
–> http://tinyurl.com/2uho7a9

http://www.intimal.edu.my/school/fas/UFLF/Papers/PP3PublishedPPCF 50 (2008) 065012 .pdf
–> http://tinyurl.com/38u9lfd

http://www.plasmafocus.net/IPFS/2010 Papers/Energies PP.pdf
–> http://tinyurl.com/346zl96

http://www.plasmafocus.net/IPFS/Papers/PP1Published APPLAB922021503_1witherratum.pdf

hmmm… a “the following string is an url” tag can be kludged… but the software’s not open source…

[Francisl]

The simple way to handle the urls is to copy the url starting from right to left and then pasting it in a new session.

[vansig]

MTd2 wrote: The papers are just about the interval up to 50KV, and this is clearly not enough since the LPPX is 45Kv. 90KV is clearly the ideal, but I don`t know the lower value. I`d have to play with the values and I`d have to play with the simulation spreadsheet first. Let me make an estimative though. Saturation occurs when all wasted energy is due the dynamical resistance. So, that means an asymptotic value of V=RI. For an optimized configuration of 100KV, see table 3, ( https://focusfusion.org/index.php/forums/viewreply/7483/ ) is about 1.5MA, we achieve a pinch saturation at 1.5MA @ 35KV. Given that we want saturation to occur at 3MA, we must double the voltage, to 70KV. Give a bit of safety margin, to avoid the flatten curve before saturation, we could say 75KV. So yes, your guess is right.

by the way, the quoted articles are using a fill pressure from 2.7 to 3.5 Torr. there are several parameters that are different in FoFu-1.
eg: How does fill pressure affect Ipeak? FoFu-1, if i recall, will be running at 40 Torr.

“the pinch current limitation is not a simple effect, but is a combination of […] the various inductances involved in the plasma focus processes abetted by the increasing coupling of C0 to the inductive energetic processes, as L0 is reduced.”

“once the model parameters have been fitted to a machine for a given gas, these model parameters may be used with some degree of confidence when operating parameters such as the voltage are varied[26,27]” —

reference 26 turns out to be online at:
http://plasmafocus.net/IPFS/modelpackage/File1RADPF.htm

and there is a calculator

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