Wendelstein 7-X

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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prestonbarrows
Posts: 78
Joined: Sat Aug 03, 2013 4:41 pm

Re: Wendelstein 7-X

Postby prestonbarrows » Thu Feb 04, 2016 12:37 am

AcesHigh wrote:this article claims Wenderlstein 7X was the first in the world ever to produce hydrogen plasma? Other fusion prototypes only produced helium plasma. Is there any veracity to that?


No. That is just a really horrible article. Here is a much better one directly from the source. http://www.ipp.mpg.de/4010154/02_16

W7X is the world's largest stellerator. Today was the first time the system has run hydrogen. Every other major fusion reactor for nearly 100 years now has used hydrogen; there is nothing inherently special or difficult about a hydrogen plasma.

Helium is generally easier to breakdown with microwave heating. This is important on a fresh system which will be full of impurities that interfere with the plasma and degrade performance. Helium is a non-reactive noble gas that does a good job of scrubbing out impurities from the walls while also being easy to pull out of the system later when you no longer want it around. Performance improves with each shot as the system is cleaned. This stage is about testing out all the diagnostics, power, vacuum, cryogenic, and other systems which need to work as a synchronized group for a successful shot.

Starting to use hydrogen is a noteworthy step since it indicates that the initial housekeeping phase is complete and the real science is starting; it makes for a nice milestone and photo-op.

D Tibbets
Posts: 2775
Joined: Thu Jun 26, 2008 6:52 am

Re: Wendelstein 7-X

Postby D Tibbets » Thu Feb 04, 2016 12:42 am

Skipjack wrote:
AcesHigh wrote:this article claims Wenderlstein 7X was the first in the world ever to produce hydrogen plasma? Other fusion prototypes only produced helium plasma. Is there any veracity to that?

Thats nonsense...


I have no idea as to the veracity of the statement, but it is mostly meaningless. Helium is traditionally the gas of choice for studying plasmas. It is safer, lends itself to leak detection, etc. Any results other than actual fusion events (measuring neutrons) is easily handled by helium and these results can be extrapolated to other gas choices.Final measurements confirming things like Bremsstruhlung characteristics in a given machine, etc may be needed as a final step, but for the basics, helium is convenient.

Having said that, and considering the computational difficulty of modeling this system, hydrogen may be more precise. The difficulty in this excuse though is that a mixture of deuterium and tritium may behave more like helium (helium4) than protium/ hydrogen. The Z and inertia of the particles may need very fine understanding. Keep in mind that if this is an ignition machine fusion produced helium4 behavior may also be a consideration.

Dan Tibbets
To error is human... and I'm very human.

Skipjack
Posts: 5954
Joined: Sun Sep 28, 2008 2:29 pm

Re: Wendelstein 7-X

Postby Skipjack » Thu Feb 04, 2016 5:12 pm

D Tibbets wrote:
Skipjack wrote:
AcesHigh wrote:this article claims Wenderlstein 7X was the first in the world ever to produce hydrogen plasma? Other fusion prototypes only produced helium plasma. Is there any veracity to that?

Thats nonsense...


I have no idea as to the veracity of the statement, but it is mostly meaningless. Helium is traditionally the gas of choice for studying plasmas. It is safer, lends itself to leak detection, etc. Any results other than actual fusion events (measuring neutrons) is easily handled by helium and these results can be extrapolated to other gas choices.Final measurements confirming things like Bremsstruhlung characteristics in a given machine, etc may be needed as a final step, but for the basics, helium is convenient.

Having said that, and considering the computational difficulty of modeling this system, hydrogen may be more precise. The difficulty in this excuse though is that a mixture of deuterium and tritium may behave more like helium (helium4) than protium/ hydrogen. The Z and inertia of the particles may need very fine understanding. Keep in mind that if this is an ignition machine fusion produced helium4 behavior may also be a consideration.

Dan Tibbets

JET (among others) certainly had experiments using hydrogen (deuterium and tritium) plasma. So I dont get why they claim to be the only ones.

crowberry
Posts: 455
Joined: Sun Sep 08, 2013 6:34 am

Re: Wendelstein 7-X

Postby crowberry » Tue Feb 09, 2016 8:15 pm

The press release after the first hydrogen plasma event in Wendelstein 7-X can be read here http://www.mpg.de/9926419/wendelstein7x-start.

The present initial experimentation phase will last until mid-March. The plasma vessel will then be opened in order to install carbon tiles for protecting the vessel walls and a so-called “divertor” for removing impurities. “These facilities will enable us to attain higher heating powers, higher temperatures, and longer discharges lasting up to ten seconds”, explains Thomas Klinger. Successive extensions are planned until, in about four years, discharges lasting 30 minutes can be produced and it can be checked at the full heating power of 20 megawatts whether Wendelstein 7-X will achieve its optimisation targets.

Maui
Posts: 553
Joined: Wed Apr 09, 2008 12:10 am
Location: Madison, WI

Re: Wendelstein 7-X

Postby Maui » Fri Jun 09, 2017 3:13 pm

Ars Technica has pretty big article up on the 7-X: Wibbly-wobbly magnetic fusion stuff: The return of the stellarator

Carl White
Posts: 305
Joined: Mon Aug 24, 2009 10:44 pm

Re: Wendelstein 7-X

Postby Carl White » Fri Jun 29, 2018 11:36 pm

https://www.techtimes.com/articles/2313 ... he-sun.htm

The stellarator has reached a temperature of 40 million Kelvin at a plasma density of 0.8 x 1020 particles per cubic meter. This was maintained for a total of 26 seconds. Operators were also able to feed it as much as 18 times more energy, reaching up to 75 megajoules of energy that was fed into the plasma.


The record-breaking fusion product was made possible by upgrading the interior components of the Wendelstein 7-X. A new lining of graphite tiles for the chamber allowed the plasma to reach higher temperatures. The lining, called a divertor, keeps the plasma in its twisting sphere while protecting it from stray particles that may make it unstable.


EDIT: here's a link to the press release from which the article is derived:

http://www.ipp.mpg.de/4413312/04_18


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