Plasma Confinement Improvement in Negative Shear Plasmas
The performance of JT-60U's negative shear plasma has been improved significantly by increasing the plasma current.
The stored energy of 9.5 MJ and energy confinement time of 0.75 s, which is the highest value in JT-60U, have been achieved at 2.4 MA with 20 MW of neutral beam injection. The central electron density reached 7.8*1019m-3 associated with the formation of internal transport barrier.
The equivalent fusion amplification factor QDT recorded the world highest value of 0.60 for negative shear plasmas.
This high performance was achieved under a condition quite relevant to a fusion reactor; namely at a moderate central ion temperature of 21 keV and with more than 70% of the neutron production rate of 4.1*1016 neutrons/s from thermal fusion reaction.
