Measurement of neutron energy on D-T fusion plasma experiments

The D-T fusion plasma experiments have been performed since November 1993 on TFTR. Tritium was introduced to the torus by gas puffing and/or by neutral beam injection (NBI). As auxiliary heatings, the NBI heating and ion cyclotron range of frequency (ICRF) heating were provided. The D-T neutron energy spectra were obtained for 'NBI and ICRF' heated plasmas and for NBI heated plasmas. These were the first D-T neutron spectra obtained from D-T plasmas in the world. The full width at half maximum (FWHM) of the peak for the ICRF heated plasma is wider than that for NBI heated plasma. The calculated energy spectra suggested this broadening was due to the existence of the high energy tritium ion tail of 100-400keV. Space resolved measurements of D-T neutron energy spectra will be necessary for ICRF heated D-T plasma experiments on the next large tokamak, such as ITER, to evaluate the mechanism of ICRF heating in the plasma. The counter telescope with thick radiator (COTETRA) will be a suitable diagnostic for this purpose because of its good energy resolution and compactness. (J.P.N.) 74 refs