4th WCSET-2015 at Japan
Special Session (Nuclear Fusion):
Title:
Development of a Novel Passive Imaging System for
Measurement of Plasma Thermal Emission
Authors:
Kishore Mishra, H. Idei, Y. Hayashi, T. Onchi, H. Zushi,
K. Hanada
Abstract:
Plasma Heating and current drive by Electron Bernstein
Waves (EBW) in tokamaks is one of the most active topic
of research at present. To excite EBWs in plasma
efficiently, microwave power needs to be launched with
an optimal angle to plasma. This required angle can be
determined by finding the viewing angle that maximizes
the thermal emission intensity from the plasma. The
usual measurement techniques employ an external scanning
mirror to steer the viewing angle and sophisticated
optical components to collect the emission from the
plasma. In this work we present a novel method of
emission measurement without the use of any moving
mirrors, optical lens, or active component. In the
absence of any mechanically active components, this
diagnostic may become very attractive for future fusion
based reactors, where restriction on available physical
space in a hostile neutron environment can be stringent.
In this diagnostic, plasma thermal emission signal from
the plasma are collected through passive waveguide
elements and their intensity and phase relationships are
precisely measured by heterodyne detection technique.
Peak emission intensity location are determined by the
phase scanning for the optimum phase matching condition.
As a proof of principle experiment, measurements with a
noise source simulating the plasma thermal emission is
done and position of the source is reconstructed
accurately. In this paper we present the development of
such diagnostic, demonstration of measurement
capabilities and some first observations from the plasma
in QUEST spherical tokamak.
Keywords: Nuclear Fusion,
High Temperature Plasma Diagnostics, Radiometer, Plasma
Thermal Emission Imaging, Phase Array Waveguide
Pages:
014-014