Recent content by johanw

I worked once in Germany in a job that required a ertificate of conduct (F\"urungszeugnis). What I understood from it, it contained all convictions of the past 5 years, only heavy crime (murder, terrorism, child abuse) of the last 20 years and war crimes never expire. But most employers outside...

In a tokamak the plasma acts as the secondary winding of a transformer, in a stellarator it doesn't so the other methods apply. On a low level: the current creates the plasma in a tokamak: the transformer creates a strong EM field, which strips some electrons from their nuclii. Those get...

Perhaps it was referring to fission products? There it is generally true that the fission products have an overabundance of neutrons.

In a plasma, ohmic resistance usually decreases when temperature rises - just the opposite as in most metals. Therefore, at some point the maximum current is what the power source can deliver but increasing the current will not heat the plasma much further. The exact quantities depend on a lot...

I just logged in after a long time and read this. How sad, and a big loss to PF. My condolences to his family and all PF members.

After finishing the Dune universe books (I am still waiting for the 3rd nosvel in the great schools of Dune series) I started with the Saga of Seven Suns from Kevin Anderson. Fortunately I found they wrote a prequel i comic form, I would advise anyone who wants to start with the series to read...

Sorry, but I don't understand that. If ##Y\neq0## and ##Q = 0##, how can then be ##T_3=0## if ##Q=T_3+Y/2##? That makes sense of course.

I had always assumed that the simplest possible standard model Higgs particle had isospin 0, but when I tried to verify this assumption I read some conflicting opinions (not to mention discussions about more complicated Higgs mechanisms). I also read conflicting views about the conservation of...

Yes, that's what ITER is supposed to do. If you are referring to http://johanw.home.xs4all.nl/afstud-l.zip : no, that's Pascal. When I graduated in 1993, Java didn't even exist yet. I work as a programmer but not on JET or any other fusion lab, I just prefer to know a little what's going...

Well, there are cheaper methods to get them on various p2p networks. I agree.

That's true, but since keeping the plasma temperature high also requires a lot of energy that doesn't really matter. It would otherwise have to be inserted in another way. No, it's the material of the reactor surrounding the plasma. It used to be made often of carbon because of its low Z (so...

Helium is a product of the fusion reaction. About 20% of the energy that is released in the reaction comes free as kinetic energy of the He nucleus (the other 80% is the kinetic energy of the neutrons, which are supposed to heat up the reactor mantle). The He nuclei interact with the plasma and...

Extracting the heavy ions alone would make the plasma electrically charged, and that causes complications you don't want. And anyway, in practice this is not a problem, maybe unless you want to extract helium, but because that is used to heat up the plasma (this is the helium that is produced in...

Well, one problem is measuring the magnetic field in real-time. It's not like hanging a probe in a plasma of this temperature works. Diagnostics are developed, and theory is being worked on. In JET they can hold the plasma stable long enough (I believe 20-30 mins), that is: if it were a real...

The magnetic field of all tokamaks contains of a combination of a poloidal field, generated by the electrical current through the plasma, and a toroidal field, generated by external coils around the plasma. Together this results in a helical field, a field that is wound around the current...