A 14-channel grating polychromator for the purpose of measuring the electron cyclotron emission (ECE) spectrum has been developed and installed on the large helical device (LHD). The grating polychromator has a Czerny-Turner setup. The main advantage of the grating polychromator is that it has a broad spectral range. Hence, it can be utilized at different magnetic field strengths. Changing the angle or replacing the grating can do this. Gratings with a grid constant of d = 2.3, 3, and 5 mm and a blaze angle of 20° can be applied and the scattered spectrum is directed to 14-liquid He cooled InSb detectors. Standard operation is performed with d = 3 mm, frange= 148-105GHz. This is second harmonic ECE for B = 2.75 T. Each channel has a spectral resolution of Δf (full width at half maximum) = 2.6 GHz or f/Δf=60 at f = 150GHz. The properties of the instrument and first experimental results of LHD ECE will be described in this article.
|Number of pages||4|
|Journal||Review of Scientific Instruments|
|Issue number||1 II|
|Publication status||Published - Jan 2001|
All Science Journal Classification (ASJC) codes