Modification of ordinary-mode reflectometry system to detect lower-hybrid waves in Alcator C-Mod

Journal Article · Mon Oct 15 00:00:00 EDT 2012 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.4734492· OSTI ID:22093929

Baek, S. G.; Shiraiwa, S.; Parker, R. R.; Dominguez, A.; Marmar, E. S. ^[1]; Kramer, G. J. ^[2]

---

1. Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States)
2. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

Backscattering experiments to detect lower-hybrid (LH) waves have been performed in Alcator C-Mod, using the two modified channels (60 GHz and 75 GHz) of an ordinary-mode reflectometry system with newly developed spectral recorders that can continuously monitor spectral power at a target frequency. The change in the baseline of the spectral recorder during the LH wave injection is highly correlated to the strength of the X-mode non-thermal electron cyclotron emission. In high density plasmas where an anomalous drop in the lower hybrid current drive efficiency is observed, the observed backscattered signals are expected to be generated near the last closed flux surface, demonstrating the presence of LH waves within the plasma. This experimental technique can be useful in identifying spatially localized LH electric fields in the periphery of high-density plasmas.

• OSTI ID: 22093929
• Journal Information: Review of Scientific Instruments, Vol. 83, Issue 10; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ALCATOR DEVICE
BACKSCATTERING
CONFINEMENT
EFFICIENCY
ELECTRIC FIELDS
EMISSION
INJECTION
LOWER HYBRID CURRENT DRIVE
LOWER HYBRID HEATING
MAGNETIC SURFACES
MODIFICATIONS
PLASMA
PLASMA DENSITY
SPECTROSCOPY