Radial characterization of wave magnetic field components during helicon discharge in a small aspect ratio torus

Wave magnetic field components are measured across the radius (−10 cm ≤ r ≤ 10 cm) for a low-pressure (0.3 mbar) helicon discharge, in a toroidal vacuum chamber of small aspect ratio. Radial variation of the wave magnetic field components, measured during the helicon mode of the discharge, exhibit strong poloidal asymmetry which contribute significantly to the wave-induced helicity. The rise in the magnitude of the radial electric field with radiofrequency power, observed during discharge mode transition, supports better radial confinement of the plasma during the helicon mode of the discharge. The strong dependence of the plasma current on the helicon mode of the discharge has been observed during the present experimental study.