Talk-Polywell.org

a discussion forum for Polywell fusion
It is currently Fri Jul 25, 2014 8:39 pm

All times are UTC




Post new topic Reply to topic  [ 34 posts ]  Go to page 1, 2, 3  Next
Author Message
PostPosted: Wed Sep 01, 2010 1:58 am 
Offline

Joined: Fri Jun 29, 2007 12:12 pm
Posts: 247
Location: Wisconsin
Well, perhaps it's a stage whisper, but there are a huge number of presentations slated for the upcoming APS-DPP meeting in Chicago in Nov, by TriAlpha researchers.

Here's the link, scroll down to the FRC section APS DPP 2010 - Session GP9

They've got a nice diagnostics suite built up, and they've tested lithium walls! One abstract also claims they've achieved large flux build-up, necessary to capture neutral beams.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Sep 01, 2010 7:11 am 
Offline

Joined: Wed Oct 07, 2009 6:15 pm
Posts: 2254
Location: Italy
Also general fusion will be present with some papers.
It's going to be a meeting of interesting people and I wonder if there will be some interesting disclosures also.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Sep 01, 2010 4:32 pm 
Offline

Joined: Mon Apr 14, 2008 2:43 pm
Posts: 986
really interesting looking conference. lots of new work with wakefield accelerators and field reversed configuration caught my eye - eg:

http://meetings.aps.org/Meeting/DPP10/Event/130411 - Formation of a Long-Lived Hot Field Reversed Configuration by Merging Two Colliding High-$\beta$ Compact Toroids - (Tri Alpha)
http://meetings.aps.org/Meeting/DPP10/Event/130513 - Characterization of plasma wake excitation and particle trapping in the nonlinear bubble regime - (LBNA)
http://meetings.aps.org/Meeting/DPP10/Event/130510 - Electron self-injection due to a plasma density downramp and gas ionization in a plasma wakefield accelerator in the blowout regime
http://meetings.aps.org/Meeting/DPP10/Event/130523 - Resonant Excitation of Plasma Wakefields ) (various)

also some interesting analytic stuff::

http://meetings.aps.org/Meeting/DPP10/Event/130507 - A Basic Analysis of Electrons Crossing a Plasma Wave and or Electromagnetic Wave (Florida)
http://meetings.aps.org/Meeting/DPP10/Event/130502 - The Physics of Reduced Models of Intense Laser-Plasma Interactions (UBL/NBNL)
http://meetings.aps.org/Meeting/DPP10/Event/130501 - Numerical methods for the 1D quasistatic wave equation (Nabraska)

i do hope they post up the presentation notes after the event.

wonder how much here might benefit Polywell research. its a double shame EMC2 are so isolated at present.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Sep 01, 2010 5:58 pm 
Offline

Joined: Mon Sep 17, 2007 5:36 pm
Posts: 105
Location: Nikaloukta
"What is even more remarkable is that the final merged FRC state exhibits a dramatic improvement in transport with flux confinement times approaching classical values. The formation of such a well-confined, long-lived, high-$\beta $ plasma state via collisional merging and magnetic reconnection should be of wide interest to fusion energy sciences and basic plasma physics research."

Pity there is no Art Carlson around to tell us if they have come up with something worth having.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 02, 2010 9:38 am 
Offline

Joined: Sun Sep 28, 2008 2:29 pm
Posts: 5082
Yeah, where did Art go anyway?
Did he get annoyed with the politics here?
Would be a pity, his opinion was always very valuable to me.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 02, 2010 10:05 am 
Offline

Joined: Wed Oct 07, 2009 6:15 pm
Posts: 2254
Location: Italy
He probably found a place where more more interesting discussions (physics wise) are going on.
Hopefully he will pop up again once he sees something worth to talk about, like the news in this thread.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 02, 2010 5:07 pm 
Offline

Joined: Thu Sep 17, 2009 11:18 pm
Posts: 4784
Location: North East Coast
As I recall, Art asked us for a PM if anything worthy came along. Of course "worthy" is completely subjective.


Top
 Profile  
 
 Post subject:
PostPosted: Fri Sep 10, 2010 8:37 am 
Offline

Joined: Mon Sep 17, 2007 5:36 pm
Posts: 105
Location: Nikaloukta
I've PM:ed dr Carlson and politely asked him whether he would like to share his views.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 06, 2010 5:20 am 
Offline

Joined: Fri Jun 29, 2007 12:12 pm
Posts: 247
Location: Wisconsin
Hmm, so I just got access to the Tri-Alpha PRL:
http://prl.aps.org/abstract/PRL/v105/i4/e045003

There's not too much technical detail to the report, but they claim some cool numbers - high flux amplification (necessary for neutral beam capture), good flux confinement time, high ion temperatures, and some hints about neutron diagnostics.

They mention that the plasma breaks up due to an m=2 rotational instability, but I believe that RMF fields are very effective at controlling such an instability -- the paper claims that a static quadrupole field was ineffective, though. They note that only the FRC configuration benefits from the flux amplification - apparently spheromaks do not get that same boost.

It'll be interesting to see if they come out with any more details about how they made the measurements, and what their future plans include. I'm guessing they'll try neutral beam injection shortly, once they optimize the existing parts of their experiment. (After all, the whole Tri-Alpha approach centers around confining the colliding proton-boron beams, as I recall.) They make a hat-tip to John Slough regarding the design of the experiment -- he actually mentioned this to me this spring when he graciously allowed me to tour his lab while I was visiting the grad school at UW.

I wish someone would do a thorough analysis of neutral background effects on these FRC experiments. I saw one report where they considered the neutrals as an injected beam, when the FRC was being translated at high speed. This might explain some of the heating when the FRC's are merged as they are in the UW and TAE experiments. Also, FRC parameters are usually underdiagnosted, and so they use a bunch of iffy approximations when calculating relevant quantities - this needs to end. And finally, someone needs to figure out what stabilizes the FRC's, once and for all.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 06, 2010 6:33 am 
Offline

Joined: Sat Dec 13, 2008 6:00 pm
Posts: 3161
Solo wrote:
I believe that RMF fields are very effective at controlling such an instability
Why?


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 06, 2010 6:34 am 
Offline

Joined: Sat Dec 13, 2008 6:00 pm
Posts: 3161
What does 'flux amplification' mean?


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 06, 2010 9:07 am 
Online

Joined: Tue May 25, 2010 8:17 pm
Posts: 3686
Probably is short for "flux density amplification" meaning that by the way they collide the two fluxes, they increased the magnitude of the flux tenfold over any other confinement system. Quite a claim, actually. The Poly is colliding fluxes off each ring. If they're getting ten times the density over a Poly, that's a noteworthy accomplishment and one I'd be interested in more detail of. $25 for a 4 page paper is pretty ridiculous though.

_________________
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 06, 2010 10:47 am 
Offline

Joined: Wed Oct 07, 2009 6:15 pm
Posts: 2254
Location: Italy
Should that be the case it might indeed be an interesting news.
I am more afraid that the 10 fold increase is referenced to some of their previous experiments, thus making the figure worthless unless they specify a value.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 06, 2010 1:15 pm 
Offline

Joined: Sun Sep 28, 2008 2:29 pm
Posts: 5082
http://nextbigfuture.com/2010/10/tri-alpha-energy-fusion-project.html

There is a small tidbit on NextBigFuture. According to this they state:
Quote:
These findings should have significant implications for fusion research and the physics of magnetic reconnection.


Now, my interpretation may be wrong, but to me this does not sound like "the end of the worlds energy problems". So, if I may say, this sounds rather discouraging, than incouraging in regards to results.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 06, 2010 3:31 pm 
Offline

Joined: Fri Jun 29, 2007 12:12 pm
Posts: 247
Location: Wisconsin
ChrisMB: It's in the U. Wash papers on their RMF experiments - I've seen the explanation, but I don't fully understand it.

Flux amplification refers to the total magnetic flux through the FRC - it basically relates to current. So flux amplification means they achieve some current drive. GIT, this amplification is from pre-collision to post-collision, and is not a comparison to other devices. The point of interest is that you have to get enough flux build-up before you can transition to neutral beam injection, or else your charge-exchange ions will have Larmor radii larger than the device size and will not be trapped (or alternatively, you will have to use a very low energy neutral beam, which doesn't help you.)

Skipjack, those are relatively bold statements in the context of a PRL. *Nobody* is going to write "the end of the world's energy problems" in a PRL -- it wouldn't make it past the editors, because that's a completely unrealistic thing to say at this point in the game.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 34 posts ]  Go to page 1, 2, 3  Next

All times are UTC


Who is online

Users browsing this forum: clonan and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group