Lawaranceville E-Newsletter

[Axil]

Audio Interview) Eric Lerner on 'TheSpaceShow.com' on 12-15-2013
Lerner discusses aneutronic fusion at Lawrenceville Plasma Physics.

http://www.portaltotheuniverse.org/podc ... ew/298553/
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Comment on this presentation as follows:

To optimize spark performance, I recommend a spark rise time of under 50 nanoseconds with a very short duration to produce the most powerful plasmoid discharge and a proportional forceful compression of the gas.

It is not the energy that the spark carries in joules. It is how fast this energy is delivered to the gas.

This is analogous to how explosives perform.

Low explosives are compounds where the rate of decomposition proceeds through the material at less than the speed of sound. The decomposition is propagated by a flame front (deflagration) which travels much more slowly through the explosive material than a shock wave of a high explosive.

High explosives are explosive materials that detonate, meaning that the explosive shock front passes through the material at a supersonic speed.

To get a better shockwave, we are interested in Pulsed power.

Pulse power is the science and technology of accumulating energy over a relatively long period of time and releasing it very quickly, thus increasing the instantaneous power.

Instantaneous power is what is important.

Steady accumulation of energy followed by its rapid release can result in the delivery of a larger amount of instantaneous power over a shorter period of time (although the total energy is the same).

For example, if one joule of energy is stored within a capacitor and then evenly released to a load over one second, the peak power delivered to the load would only be 1 watt.

However, if all of the stored energy were released within one microsecond, the peak power would be one megawatt, a million times greater.

The release of all the power stored in the focus fusion capacitors should be released in 10 nanoseconds.

The higher the voltage rating of the discharge capacitors, the faster is the speed of the spark discharge and the larger is the instantaneous power pulse.

The capacitors that focus fusion should use should be rated at 3 million volts, the capacity in amps is not that important. Currently, the FF capacitors are only rated at 45,000 volts.

The speed of the spark will kept the electrode material close to the electrode eliminating contamination of the plasma. By the way, the high voltage strategy (a few nanoseconds) is what Brillouin Energy is using to kept there wire from melting.

[GIThruster]

Yes well, the highest voltage capacitors in the world are probably 50kV. Saying you need 3,000kV is like saying (after the fact) that your process can't work.

Disappointing.

However, it is certainly possible to create such capacitors. The question is really one of safety. Is anything at Lawrenceville hardened to 3MV? I'd think they'd need an entirely new reactor setup.

[zapkitty]

Saying you need 3,000kV is like saying (after the fact) that your process can't work.

Nope, you misunderstood Axil: Eric Lerner said no such thing.

Axil was the one proposing 3 megavolt capacitors... not Lerner.

The 45 kV that the present caps are rated for is all that should be needed for the test unit to reach its goals.

[Axil]

Yes well, the highest voltage capacitors in the world are probably 50kV. Saying you need 3,000kV is like saying (after the fact) that your process can't work.

Disappointing.

However, it is certainly possible to create such capacitors. The question is really one of safety. Is anything at Lawrenceville hardened to 3MV? I'd think they'd need an entirely new reactor setup.

Dynamitrons are capable of pulses up to 5 megavolts. Do some research.

[GIThruster]

Although dynamitrons can deliver 5MV, they deliver it in small mA for about a millisecond, which is not enough to form a plasmoid. Learner is using plasmoids from about 100kA for about a single millisecond. Dynamitrons can't do that. But as Kitty notes, Eric hasn't said their caps can't do the job, so . . .

[Axil]

Although dynamitrons can deliver 5MV, they deliver it in small mA for about a millisecond, which is not enough to form a plasmoid. Learner is using plasmoids from about 100kA for about a single millisecond. Dynamitrons can't do that. But as Kitty notes, Eric hasn't said their caps can't do the job, so . . .

The Dynamitron® direct-current accelerator has been upgraded from 200 kW to 300 kW of electron beam power at 5.0 MeV. The emitted X-ray power with 8% power conversion efficiency is 24 kW, which can provide INAC 2009, Rio de Janeiro, RJ, Brazil nearly the same processing capacity as 2.0 MCi of cobalt-60 sources.

RADIATION PROCESSING WITH HIGH-ENERGY X-RAYS
Marshall R. Cleland and Frédéric Stichelbaut

the pulse duration is 1.3 nanoseconds.

This system is all based on the performance of the cap array. Eric will find that out someday.

[ladajo]

Did you read your own post?

the pulse duration is 1.3 nanoseconds.

Lerner, as stated is looking for 100Kw for a millisecond or so, not 300Kw for 1.3 nano seconds. Can you see the magnitudes of difference between "nano" and "milli"?

[Axil]

Did you read your own post?

the pulse duration is 1.3 nanoseconds.

Lerner, as stated is looking for 100Kw for a millisecond or so, not 300Kw for 1.3 nano seconds. Can you see the magnitudes of difference between "nano" and "milli"?

Nano is far better than milli. IF Lerner had a faster spark, he would be where he wants to be by now. In a few years, this fact will dawn on him.

[ladajo]

I currently do not agree with your point about fast spark. That said, this is a relatively new approach and it may turn out to be that faster/stronger is the way to go. I am thinking, however, that in order to simplify engineering needs, as well as ignition dynamics, slower is probably better.

We shall see. Neither of us can claim certainty at this point.

[Axil]

I currently do not agree with your point about fast spark. That said, this is a relatively new approach and it may turn out to be that faster/stronger is the way to go. I am thinking, however, that in order to simplify engineering needs, as well as ignition dynamics, slower is probably better.

We shall see. Neither of us can claim certainty at this point.

Keeping things as they are now in terms of joules per unit time, if focus fusion can increase their spark speed by 1000 (nano vs. milli), then FF could reduce their amperage by 1000 for the same yield of instantaneous power. That 1000 fold reduction in amperage should greatly reduce the cost of the capacitor bank and the total cost of the FF reactor.

That is why nano is better: it makes reactor hardware much cheaper.

[ladajo]

Maybe. It well may cause other issues in ignition control and material selections that offset that.

We shall see.

[Axil]

Maybe. It well may cause other issues in ignition control and material selections that offset that.

We shall see.

The Dynamitron can be operated in e-beam or x-ray modes to produce high current pulses in the range from 1 ms to continuous.

One future problem that FF will have is the limited rate of the charge/discharge cycles that its capacitor bank can accomplish in a given timeframe. A large volume of amperage must be pumped into those capacitors and the charge rate is exponentially slow.



The Dynamitron can produce pulses at a minimum of 1000 times a second all the way up to continuous operation.

[GIThruster]

Keeping things as they are now in terms of joules per unit time, if focus fusion can increase their spark speed by 1000 (nano vs. milli), then FF could reduce their amperage by 1000 for the same yield of instantaneous power. That 1000 fold reduction in amperage should greatly reduce the cost of the capacitor bank and the total cost of the FF reactor.

That is why nano is better: it makes reactor hardware much cheaper.

The plasmoid takes time to form and compress. I seriously doubt you know Lerner's business better than he does.

[D Tibbets]

A nano second seems a very short time to accelerate and compact a plasma. The inertia of the plasma ions need to be considered. Lets see, light travels ~ 300 meters in 1 micro second and ~ 0.3 meters in 1 nanosecond. Any matter will be traveling much slower. Too fast of a collapsing magnetic field would leave the ions behind. Lots of heat might be generated, but collapse into a small central space in a coherent fashion would seem severely impaired. This simple viewpoint may be flawed but seems limiting to me. Collapsing over 10s to hundreds of nanoseconds or even microseconds sounds more realistic. It is not so much how fast the plasmoid forms, but how long it persists with a relatively high density and energy of the contained ions. Inertia plays a role.

Also, from a simple particle velocity / energy perspective if the ions are accelerated to a million or more eV before they converge in the center, this energy is higher than the optimal energies for fusion crossection for DT, DD or pB11. So, either you waste input energy by inefficiently accelerating the ions in a cohesive manner, or you waste energy by having excessive energy conditions for the most efficient fusion rates. Of course there are tradeoffs, that is what the triple product is all about, but it would seem to be a losing proposition. You might have a higher temperature (more than you want), but the confinement time will be less, and the volume would possibly be less, so the focus/ density would need to be much (?) higher to get the same final triple product. The precision of the plasmoid formation would need to be greater, possibly much greater than is reasonably achievable within the engineering precision possible. It is a Goldilocks situation.

The DPF seems to scale better with smaller size. I guess that this is due to considerations for producing a good geometric plasmoid with fusion temperatures and density , but also results in smaller reaction volumes. At some point the shrinking volume becomes the dominate factor, so there is a sweat spot that determines the few MW fusion output that can be optimally produced with optimal input costs.

Dan Tibbets

[D Tibbets]

To justify my above post, consider...
Generally when electrostatic acceleration is considered, an attraction/ repulsion between two point charges is considered. This is determined by charge intensity and separation distance. If Gauss law is applied in certain situations (near infinite plane) distance becomes less important. But this ignores time and inertia. I wonder if time was considered at what point would it become dominate. If an ion is exposed to a accelerating charge for 1 second, then it will achieve very close to the final energy available from the accelerating field. But at 1 microsecond, one nanosecond, how much does inertia impead the attainment of the final potential acceleration? Obviously, there is an absolute where effectively zero acceleration is possible. This would be at Plank time scales, which is very short times indeed. But is the time needed to overcome inertia significant at nanosecond time scales for heavy ions, and for that matter light electrons? Will there be significant charge separation due to this? Is that harmful? ...

Dan Tibbets