Youtube: Eric Lerner May 14th talk at the Oxford Scientific Society

[zapkitty]

On May 14th Eric gave a talk on Focus Fusion to the Oxford Scientific Society and now LPP has put a vid up:

http://www.youtube.com/watch?v=8PnyDRDUMwQ&feature=youtu.be&a

There was also a version put up earlier in three segments, and these include the Q&A session that followed:

1. http://www.youtube.com/watch?v=4QA3733aFfI
2. http://www.youtube.com/watch?v=nXYL3lEmKHg
3. http://www.youtube.com/watch?v=UYliRKrEJww

… the Q&A starts at 12 minutes into the second link.

[Joeviocoe]

Awesome videos.

Three questions I had that was almost answered.

Lerner mentioned that sputtering (causing the deformation of the electrodes and requiring monthly replacement/re-depositing)… would increase again a bit going from Tungsten to Beryllium. Undoing some of the improvements going from Copper to Tungsten.

1) But what about electrode vaporization for Beryllium from 2.8 MA of current? Would that undo much of the benefits for going from Copper to Tungsten?

2) Would Beryllium electrodes cause impurities which reduce yield? (even though the atomic mass is 7 times lighter than copper)

3) Would the Beryllium electrodes need a thin surface plating of Tungsten (similar to how the Copper electrodes were Silver plated)… to prevent the loss of proper filaments and reduce vaporization?
Or would that thin surface absorb too much X-Rays and burn up?

Thanks.

[zapkitty]

Joeviocoe wrote:

Lerner mentioned that sputtering (causing the deformation of the electrodes and requiring monthly replacement/re-depositing)… would increase again a bit going from Tungsten to Beryllium.

1) But what about electrode vaporization for Beryllium from 2.8 MA of current? Would that undo much of the benefits for going from Copper to Tungsten?

Yes, but while tungsten’s properties of hardness and heat resistance will be very helpful in the next, intermediate, stages of research that same tungsten will become worse than useless as the x-ray flux approaches breakeven conditions.

The x-rays will take out the tungsten. And then tungsten everywhere except where it’s supposed to be.

… but the LPP team intends to use this time with the tungsten to, among other things, learn the best techniques for reducing the runaway electrons that do so much to erode the electrodes.

The plan is that when they finally have to switch to beryllium that what they’ll have learned from working with the tungsten will help them keep the Be erosion to manageable levels.

Joeviocoe wrote: 2) Would Beryllium electrodes cause impurities which reduce yield? (even though the atomic mass is 7 times lighter than copper)

If they can’t keep the erosion levels down then it’ll become a moot point.

Joeviocoe wrote: 3) Would the Beryllium electrodes need a thin surface plating of Tungsten… … Or would that thin surface absorb too much X-Rays and burn up?

Per Lerner it would vaporize and crack the electrode surfaces.

[Henning]

Joeviocoe wrote:
3) Would the Beryllium electrodes need a thin surface plating of Tungsten (similar to how the Copper electrodes were Silver plated)… to prevent the loss of proper filaments and reduce vaporization?
Or would that thin surface absorb too much X-Rays and burn up?

No. Beryllium is chosen because it’s transparent to x-rays. Plating the electrodes with Tungsten is as if you’re painting them black.

[nakile]

The cycles per second caught my attention. I’ve been assuming that a unit could be throttled by lowering the number of cycles per second, but Eric states after 52:55 into the first video that the cycle rate can’t be too low or else the boron gas would participate onto the electrode, making 200 cycles per second “about right.”

So does this mean a reactor would be more of an “on or off” type of device? What could be done for loads lower than 5 MW?

[Di Vita]

@ zapkitty

“what they’ll have learned from working with the tungsten will help them keep the Be erosion to manageable levels.”

This is likely to be troublesome. Berillium is usually considered a poisonous material, and its utilisation is subject to nuclear-grade regulations in the EU (I dont’ know about USA). For example, QinetiQ in the UK sells its own know-how in safe (?) berillium machining; it relies on decades of nuclear military expertise at Atomic Weapon Establishment, Aldermaston. Inclusion of berillium coating in future Plasma Focus is far from trivial: costs may be skyrocketing.

[Tim1]

Di Vita wrote:
Inclusion of berillium coating in future Plasma Focus is far from trivial: costs may be skyrocketing.

They aren’t coating anything, it’s solid beryllium. It’s use is necessary to prevent X-ray absorption. It requires special precautions, but there are a number of companies in the nuclear and aerospace industry that have the technology.

[Di Vita]

@ Tim1 “there are […] technology”. You have a point. All the same, I still guess berillium may heavily affect the attractiveness of future Plasma Focus reactors, as both safety and financial breakdown are at stake. I mean, it comes to me an old Donald Duck story, where the hero used to drive an amazing oil-free Ferrari-like car, whose only weak point was the fuel cost: 1 billion US$ / Km…

[Author]

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