Projected Neutron Emission Spectroscopy Diagnosis of Jet Deuterium Plasmas

Abstract

The DT experimental campaign on JET (1997) represented a major step forward for neutron emission spectroscopy (NES) diagnostics thanks to the high count rate measurements obtained with the magnetic proton recoil (MPR) neutron spectrometer in high fusion yield plasmas. NES measurements were made on JET DT plasmas¹ for different heating conditions such as NB injection or ICRH using, e.g., the (D)T minority scheme². A multiple-component model has been developed for analysis of DT neutron spectra that is based on a simplified description of fuel ion velocity distributions for different heating conditions^3,4. The same model is used here for projections of NES spectra from JET deuterium plasmas using the DT results as input. This is done on the basis of a system of two complementary NES instruments, the TOFOR (Time of Flight - Optimized Rate)⁵ and MPRu (Magnetic Proton Recoil Upgrade) spectrometers that are presently proposed for installation on JET⁶. Both spectrometers would record neutron spectra in D plasmas but for different viewing lines. TOFOR would have a “vertical” view, i.e. at an angle of 90° relative to the toroidal magnetic field. This is the same viewing line used for some of the previous dd NES measurements on JET⁷. MPRu would have a “tangential” view, i.e. horizontal (on the equatorial plane) at an angle of 47° relative to the toroidal magnetic field and opposite to the beam injection direction. This is the same viewing line used for the 1997 DT measurements using the MPR spectrometer.