UK Culham Fusion visit - what questions to ask?

[Nick Barsley]

Hi All,

I'm going on a public trip around the UK's Culham Fusion Research Centre in a week's time. The tour is led by their scientists there, and takes the small group of us "public" around the JET (Joint European Torus) and MAST (Mega Amp Spherical Tokamak) experiments.

I'm going to take the opportunity to ask a lot of questions, and would be happy to post back the scientists replies on this message board.

The questions I want to ask concentrate on the Polywell theory and design.

I've a few in mind from:
- Extent to which the design thermalises towards Maxwellian, losing the necessary well depth for breakeven fusion rate (esp. for pB11?)
- Bremsstrahlung radiation losses (closely linked to the above)
- Latest thinking on direct electricity conversion from helium ions
- Paschen arcing
- Degradation of the walls (interested in how JET and MAST overcome this, what their materials are, cooling flow rates, etc...

What would be other / sharper / better questions to ask?

I'll gladly post back their replies,

Best regards, Nick

[ladajo]

You might not get much love or understanding from them regarding Polywell. But, by all means, have at it!

[mattman]

Hey,

This may be clearer way to frame your question...

Ask them if anyone has measured light radiated from a plasma cloud as a function of temperature.

This includes the X-rays, UV, IR and Visible

Basically it is this plot:



You could just print out this picture and show it too them.

[kcdodd]

I can tell you those types of measurmenets are quite common. I've done a little in the visible spectrum at low temperatures.

[hanelyp]

Re: Matman's graph:

Blackbody radiation scales with T^4. Non-Maxwellian energy distribution may be a factor here.

Fusion power follows a curve peaking at a temperature dependent on fuel and energy spread, then declining again.

Not sure how well it applies to magnetically confined plasma, but at more ordinary temperatures, heat conduction is mostly linear with temperature.

[D Tibbets]

More in keeping with their actual experience/ plans...

what are the goals and expectations of new work with the upgraded JET compared to the old? Changes in input heating, magnetic field management with attention to instabilities, and output goals. Will output improve or is the new work concentrating on various minute controls of instability and energy input?

And, a practical consideration. Do they hope to improve on maintainable Beta with associated increased plasma density and associated fusion output per unit of volume? This is very important in pushing for an actually practical Tokamak power plant,

Dan Tibbets.

[asdfuogh]

You might not get much love or understanding from them regarding Polywell. But, by all means, have at it!

I think it's more likely that any scientist will be more of an expert in their own specialization and would prefer not to comment on things outside of their expertise because it's a bad political move. You know, unless the scientist is a super bigshot who can take hits like that.

[chrismb]

What would be other / sharper / better questions to ask?

Print this out and read it, word for word;

"You have published papers saying that you've shown how ICRH and neutral beam heating work together better that either one on its own. What is your argument to say that you are SURE this is nothing to do with entropy mitigation at the plasma edge from work done on ions by rotating radial electric fields in the near fields of the antennae elements, and if you are NOT sure about it then what would you say to an inventor that has a patent for this method and who says you are ignoring his patent rights?"

If you have any senior staff there when you ask that question then direct your question to Steve Cowley, William Morris or Eric Hollis, if they're there. Watch their faces turn white (or red). Do it towards the end of questions in case they cut your visit short....

[ladajo]

You might not get much love or understanding from them regarding Polywell. But, by all means, have at it!

I think it's more likely that any scientist will be more of an expert in their own specialization and would prefer not to comment on things outside of their expertise because it's a bad political move. You know, unless the scientist is a super bigshot who can take hits like that.

Yup. Part of my point indeed.

[Nick Barsley]

Thanks everyone - I really appreciate all the good questions and ideas. I'll take note book and camera and report back. Really looking forward to it!