Determination of the deuterium temperature profile in magnetic fusion plasmas

Abstract

Summary. --A new experimental method for determining the radial deuterium temperature profile TD (R) in axisymmetrical toroidal fusion plasmas is presented. The method is based on a generalized Abel inversion of neutron brightness data providing the radial neutron emissivity profile of the plasma. This profile, combined with information on the deuterium density profile, is used to determine TD (R) under the assumption that the ion velocity distribution is Maxwellian. Results are presented here from the analysis of JET data. It is found that, for typical JET plasma conditions, the dominant source of uncertainty arises from the high plasma impurity level and the fact that it is poorly known; these problems can be expected to be remedied and neutron brightness measurements would be expected to be very effective (especially in high-density plasmas) as a TD (R) diagnostics. PACS 52.70.Nc -Particle measurements. PACS 52.25.Tx -Emission, absorption, and scattering of particles. -I n t r o d u c t i o n .As magnetically confined plasmas achieve conditions approaching ignition, higher fusion rates are obtained and new neutron diagnostic measurements become possible. The J E T machine is an example of such plasma physics experiments allowing for new neutron diagnostics to be tested. These measurements are at present in many respects a complement to other diagnostic data. However, future experiments using D-T plasmas are expected to depend critically on neutron-based information, and better neutron measurements are also being proposed which take full advantage of the expected high fusion rates [1]. It is, therefore, of interest to discuss in some detail what kind of information one can deduce from fusion neutron measurements. This can be done by studying the data from present experiments. An example of such new data comes from measurements of the line-integrated neutron emissivity of the plasma, i.e. the neutron brightness. The purpose of this paper is to present a new experimental 319

Neutron spectrometry in compact ignition experiments

“…In principle, even the T~ profile can be derived from the emissivity data from the cameras as done in [42]. NS data in context of other diagnostics.…”