Relative frequency calibration for fast frequency sweep microwave reflectometry

Akira Ejiri, Yoshiyuki Shimada, Takuma Yamada, Takuya Oosako, Yuichi Takase, Hiroshi Kasahara

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


A frequency-modulated reflectometer with a frequency band of 26.5 to 40GHz has been constructed and installed in the TST-2 spherical tokamak to measure fast density profile evolution. In order to calibrate the instantaneous frequency for various frequency sweep rates, a waveform matching method has been proposed and applied to the reflectometer. This method compares the interference patterns (i.e., waveforms) of a fixed target reflection, which do not depend on the sweep rate, and obtains the instantaneous frequency by fitting the target waveform time to the time for a reference sweep waveform. This allows evaluation of output frequency stability. The overall frequency error, including reproducibility, is around 0.1 GHz. Sweep rates up to 20 μs were used to measure the density profile evolution during rf heating.

Original languageEnglish
Article number040
JournalPlasma and Fusion Research
Publication statusPublished - 2007

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics


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