title: Hard x-ray correlation analysis as a diagnostic tool for the measurement of magnetic turbulence in tokamaks.
abstract: A diagnostic has been developed for the measurement and characterization of the magnetic turbulence occurring in the core region of a tokamak. A specially shielded detector looking in the tangential direction has been employed to measure the thin target bremsstrahlung from the core plasma. The thick target bremsstrahlung from the limiter is also recorded at the same time. Auto- and cross-correlation analyses have been shown to yield, respectively, the stochasticity of the magnetic fluctuations in the core region and the consequent diffusion coefficient of the nonthermal electrons. The measured stochasticity bears a relationship with the diffusion coefficient. Data obtained from internal magnetic probes corroborate the above trend but the hard x-ray measurement data are shown to be more reliable than those obtained from magnetic probes.
authors.affiliation: Plasma Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India.
authors.forename: S K
authors.initials: SK
authors.lastname: Saha
authors.forename: A K
authors.initials: AK
authors.lastname: Hui
authors.forename: S
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Santwana
authors.initials: S
authors.lastname: Raychaudhuri
authors.forename: D
authors.initials: D
authors.lastname: Banik