Two-color terahertz interferometer based on the frequency-splitted orthogonal polarization modes of the water vapor laser and designed for measuring the electron density profile in the L-2M stellarator
- Russian Academy of Sciences, Prokhorov Institute of General Physics (Russian Federation)
- Russian Academy of Sciences, P.L. Kapitza Institute for Physical Problems (Russian Federation)
An upgraded diagnostics for measuring the electron density profile in the L-2M stellarator is proposed. The existing diagnostics employs an interferometer based on an HCN laser with a mechanical frequency shifter and unmagnetized InSb detectors cooled with liquid helium. It is proposed to replace the HCN laser with a water vapor laser operating simultaneously at two wavelengths (220 and 118 {mu}m). Being equipped with an anisotropic exit mirror, the water vapor laser allows the generation of orthogonally polarized, frequency-splitted modes at each of these wavelengths with a frequency difference of several tens of kilohertzs. Such a scheme makes it possible to get rid of the mechanical frequency shifter. Moreover, simultaneous measurements at two wavelengths allow one to reliably separate the phase increments introduced by the plasma electron component and by variations in the lengths of the interferometer arms. To take full advantage of this scheme, specially developed cryogenic receivers consisting of Ge and InSb photodetectors placed one after another will be used. To increase the response of the system near {lambda} = 220 {mu}m, the InSb detector is placed in a Almost-Equal-To 0.55-T magnetic field.
- OSTI ID:
- 22047576
- Journal Information:
- Plasma Physics Reports, Vol. 34, Issue 3; Other Information: Copyright (c) 2008 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-780X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ANISOTROPY
COLOR
ELECTRON DENSITY
ELECTRONS
HYDROCYANIC ACID
INDIUM ANTIMONIDES
INTERFEROMETERS
L-2 STELLARATOR
LASERS
MAGNETIC FIELDS
MIRRORS
PHOTODETECTORS
PLASMA
PLASMA DIAGNOSTICS
PLASMA PRODUCTION
POLARIZATION
WATER VAPOR