Plasma diagnostics on large tokamaks

Abstract

The main tasks of the large tokamaks which are under construction (T-15 and Tore Supra) and of those which have already been built (TFTR, JET, JT-6O and DIE-D) together with their design features which are relevant to plasma diagnostics are briefly discussed. The structural features and principal characteristics of the diagnostic systems being developed or already being used on these devices are also examined. The different diagnostic methods are described according to the physical quantities to be measured: electric and magnetic diagnostics, measurements of electron density, electron temperature, the ion components of the plasma, radiation loss measurements, spectroscopy of impurities, edge diagnostics and study of plasma stability. The main parameters of the various diagnostic systems used on the six large tokamaks are summarized in tables.

Tokamak physics experiment: Diagnostic windows study

“…1 p m (Refs. 3,4). An estimated distribution of percent energy versus wavelength is 80% at 40-60 8, from carbon, 10% at 15-20 8, from oxygen, and 10% in the range of loo0 A from hydrogen.…”

Bolometers for Fusion Plasma Diagnostics

“…But there is a need for a preamplifier near the detector. Also it is sensitive to radiation damage, which begins to take effect from a 1 MeV neutron fluence of  5 x 10 14 ncm 2 (Orlinskiz and Magyar, 1988). These detectors have been used in DIVA (Odajima et al1978), ISX-B (Bush and Lyon, 1977) and TFR (TFR groups, 1980) tokamaks.…”

An infrared interferometer for investigating subthermonuclear plasma in the GOL-3 multimirror trap

“…In this case, the deflection of the probing beam in the region of the detector's light sensitive element (1-2 m from plasma) is ~0.01 mm, which is much smaller than the interference fringe width (>5 mm) that is practically attained during tuning. When evaluating the vibra tion induced noise, it is reasonable to assume that the vibration spectrum of the large GOL 3 facility is anal ogous to the spectrum of large tokamaks, such as D III or JET, where the measured amplitude of vibra tions of structural elements is ~100 μm at a character istic frequency of 100 Hz [1,8]. The experience has shown that such a vibration level on the GOL 3 facility can be efficiently suppressed using a 1 m long frame, whose columns have a cross section of 15 × 20 cm 2 .…”