High temperature experiments and fusion product measurements in JET

High temperature plasmas (Ti ≤ 23 keV and Te ≤ 12 keV) have been obtained in JET using NBI and ICRH. The low target densities required for these experiments were produced by using graphite surfaces to pump the plasma. Low density helium pulses were employed to deplete the graphite of deuterium, thereby enhancing the pumping effect. The trapping and slowing-down rates for the ICRH minority ions and d-d tritons were close to the classical values. Although the ICRH minority ions carried as much as one third of the total energy content, the thermal plasma energy confinement was unaffected by their presence. The high temperature plasmas had the same plasma energy confinement as high density, low temperature plasmas, and the heating rates of hot electron and hot ion discharges were similar. These results show that the prospects are good for α-particle heating and high temperature operation in thermonuclear plasmas. (author). 8 refs, 5 figs