Spectroscopy for Impurity Control In ITER
Spectroscopic diagnostics on existing tokamaks can be adapted to ITER using reflectors in labyrinthine optical paths. The greatest obstacle to this approach is the performance and integrity of the first reflector. However, with this approach to neutron screening, radiation induced noise can be reduced to acceptable levels. There is no single white light reflector (WLR) with complete wavelength coverage between 1 angstrom and 1 um. Above 300 angstroms, mirrors can give adequate reflectivity and screening against neutrons and gamma-rays. In this long wavelength region there is a possibility of multichord arrays from a single reflector with F/6 aperture. In the X-ray region no ideal WLR exists but several limited bandwidth regions covering important wavelength regions, are feasible. This implies the installation of several viewing chords or a single chord with moving diffractors or reflectors. Innovative techniques are being investigated but a broadband survey using a single static element is not possible in the X-ray region. The XUV and VUV region presents the most technically demanding problems. it should not be neglected since this region holds essential information on the mantle and divertor plasmas. Windows to isolate tritium contamination cannot be used, so continuously pumped cavity containing the relay optics and spectrometers must be employed. A radical approach would be to remove all windows and use multiple straight through, vacuum beamlines similar to and possible sharing diagnostic functions with the neutron camera.
Bibliographic Reference: Article : Workshop for Diagnostics for ITER (1995)
Record Number: 199512135 / Last updated on: 1996-01-15
Original language: en
Available languages: en