Engineering topics

Wukitch, Steve

Publications and source records attributed to Wukitch, Steve.

3 records

DOE OSTI2019

Identification of waves in the lower-hybrid frequency range in the scrape-off layer plasma of Alcator C-Mod

Polarization resolved measurements of the parallel refractive index Nk ≡ ckk/ω of the driven RF waves in the lower hybrid (LH) range of frequencies are performed using arrays of RF magnetic probes in the scrape-off layer plasma of Alcator C-Mod. The measured Nk of the RF magnetic field component parallel to the background magnetic field is about -1.6, which corresponds to the peak of the launched LH Nk spectrum. Based on the wave dispersion relationship, this wave is identified as the LH slow wave. On the other hand, the RF magnetic field component perpendicular to the magnetic field is found to have a lower Nk of -1.2, and is detected only near the last closed flux surface. This wave is identified as the LH fast wave generated by slow-fast wave mode conversion.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2016

Identification of waves in the lower-hybrid frequency range in the scrape-off layer plasma of Alcator C-Mod

We report polarization resolved measurements of the parallel refractive index $N_∥≡ck_∥/w$ of the driven RF waves in the lower hybrid (LH) range of frequencies are performed using arrays of RF magnetic probes in the scrape-off layer plasma of Alcator C-Mod. The measured $N_∥$ of the RF magnetic field component parallel to the background magnetic field is about –1.6, which corresponds to the peak of the launched LH $N_∥$ spectrum. Based on the wave dispersion relationship, this wave is identified as the LH slow wave. On the other hand, the RF magnetic field component perpendicular to the magnetic field is found to have a lower $N_∥$ of –1.2, and is detected only near the last closed flux surface. This wave is identified as the LH fast wave generated by slow-fast wave mode conversion.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2010

Scrape-off layer reflectometer for Alcator C-Mod

A swept-frequency X-mode reflectometer is being built for Alcator C-Mod to measure the scrape-off layer density profiles at the top, middle, and bottom locations in front of both the new lower hybrid launcher and the new ion cyclotron range of frequencies antenna. The system is planned to operate between 100 and 146 GHz at sweep rates from 10 {mu}s to 1 ms, and will cover a density range of approximately 10{sup 16}-10{sup 20} m{sup -3} at B{sub 0}=5-5.4 T. To minimize the effects of density fluctuations, both differential phase and full phase reflectometry will be employed. Design, test data, and calibration results of this electronics system will be discussed. To reduce attenuation losses, tallguide (TE{sub 01}) will be used for most of the transmission line system. Simulations of high mode conversion in tallguide components, such as e-plane hyperbolic secant radius of curvature bends, tapers, and horn antennas will be shown. Experimental measurements of the total attenuation losses of these components in the lower hybrid waveguide run will also be presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗