D Tibbets wrote:Another question is what are they changing from previous tests. Higher temperatures, higher B fields, better control of edge instabilities, Beta pushed a little further.... ? Do they hope to reach ignition ?
JET still holds the record for experimental Q; this required the use of D-T and was set way back in '97 I believe. Other tokamaks like JT-60 have since demonstrated 'equivalent Q's' using D-D which have passed break even. But of course, the proof is in the pudding. Even if the extrapolation from D-D to D-T is well known and accepted, no fusion reactor (short of a thermonuclear bomb) has yet demonstrated actual break even operation.
In the mean time, JET has learned from these newer reactors and has been upgraded with ITER-like parts which are hoped to improve performance. Many of these upgrades have to do with the wall materials and divertor, parts which dictate the purity of the plasma. The input power systems such as the Neutral Beam Injectors were also overhauled to higher power levels since the '97 record shot.
Basically, JET is one of the only tokamak facilities equipped to handle tritium until ITER comes online (hopefully sometime within the next century). It would be a wonderful demonstration if they could experimentally show true break even for any length of time.