Status of far infrared tangential interferometry/polarimetry system on NSTX (abstract)
Measurement of the core B{sub T}(r,t) value is essential in National Spherical Torus Experiment (NSTX), since effects of paramagnetism and diamagnetism in the Spherical Torus are expected to be considerably greater than that in higher aspect ratio tokamaks. Therefore, plasma parameters dependent upon B{sub T} such as the q-profile and local q value cannot be evaluated without independent measurement of B{sub T}(r,t). The multichord tangential far infrared interferometer/polarimeter (FIReTIP) system currently under development for NSTX will provide temporally and radially resolved toroidal field profile [B{sub T}(r,t)] and two-dimensional (2D) electron density profile [n{sub e}(r,t)] data. The seven channel system is based on three FIR lasers including the Stark tuned FIR laser operating at 119 {mu}m which is an optimum wavelength for NSTX plasma parameters. The optical system is configured as a Michelson system using retroreflectors. The final system design is completed and initial two channels will be installed this fiscal year to support NSTX operation. The channel spacing of FIReTIP system is optimized via data analysis with various expected electron density and magnetic field profile shapes. In simulation study, the solution of self-consistent magnetohydrodynamics equilibrium was used to project a diamagnetic effect on the toroidal magnetic field. A detailed inversion process based on assumed profiles of the electron density and self-consistent toroidal field is exercised to estimate the source of errors for both local density and local magnetic field. The outcome of the proposed system is crucial to the study of confinement, heating and stability of NSTX plasmas.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40204778
- Journal Information:
- Review of Scientific Instruments, Vol. 72, Issue 1; Other Information: Othernumber: RSINAK000072000001001067000001; 738101CON; PBD: Jan 2001; ISSN 0034-6748
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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