Taking account of two-fluid effect Mahajan-Yoshida has developed a new relaxation theory which should satisfy the following two relaxation conditions: B=a(V-∇×B), B+∇×V=bV, where B is a magnetic field, V is a plasma flow, a and b is constant[1]. According to this theory the plasma flow confines high beta plasma. The toroidal device with an internal coil is suited to explore this theory. Consequently we have constructed an internal coil device Mini-RT with high temperature superconductor (HTS) coil. The toroidal plasma flow is driven by a radial electric field and a poloidal magnetic field with E×B drift velocity. The magnetic field is produced by the internal HTS coil and the electric field will be produced by inserting an electrode in the plasma directly or by a direct orbit loss of high-energy electrons[2]. Here we are planning to study whether relaxation conditions are met or not by measuring the radial profiles of the toroidal plasma flow and the poloidal magnetic field simultaneously. In order to measure the radial profile of the plasma flow we set up a spectroscopy. The spectroscopy has a Czerny-Turner spectrometer (focal length of 1.0m, Grating of 1800grooves/mm) and a cooled charge coupled device (CCD). By setting up a cylindrical lens at the exit slit of the spectrometer, the resolution of the wavelength in increased up to 2pm/pixel. Moreover we add a corrector of aberration for measurement of spatial resolution and two sets of optical fiber arrays that view face to face in the toroidal direction for an accurate measurement of the plasma flow. These systems enable us to measure the toroidal rotation velocity up to 1km/sec, which is induced with the radial electric field of 100V/m at the magnetic field of 0.1T. We plan to measure the magnetic field in the poloidal direction by pick up coils to investigate the relaxation conditions with B and V.

References