1. The 14-channel grating polychromator for ECE measurements in LHD.
- Author
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Kawahata, K., deVries, P. C., Nagayama, Y., Inagaki, S., Tokuzawa, T., Tanaka, K., and Sasao, H.
- Subjects
SPECTRUM analysis instruments ,DIFFRACTION gratings - Abstract
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, f[sup range]=148–105 GHz. 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=150 GHz. The properties of the instrument and first experimental results of LHD ECE will be described in this article. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2001
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