Magnetic fluctuations in CASTOR tokamak and their relationship with the electrostatic fluctuations

Abstract

Summary form only given. The magnetic fluctuations are monitored in radial and poloidal directions deep (upto r/a=0.4) into the CASTOR tokamak and their relationship with electrostatic fluctuations is studied. For performing the experiments CASTOR was operated with: R=0.40 m, a=0.085 m, B/sub T/=1 T, I/sub p/=12 kA and n~/sub e//spl les/10/sup 19/ m/sup -3/. A set of eight magnetic probes (all of them 4 mm in length and 4 mm in diameter), with all the probes registering the radial component of the magnetic field and radially spaced on each other, is constructed to study the radial magnetic field fluctuations (B~r). With this set the whole radial profile from r/a=1 to r/a=0.4 could be achieved for each shot. The radial correlation length and propagation velocity of B~r are computed. For further diagnosing the relation between the magnetic and electrostatic fluctuations a new experiment has been conceptualised. A rogowski coil has been constructed and a Langmuir probe is installed in the center of the coil. The rogowski coil has a diameter of 1 cm with 300 number of turns wound on a circular form and a cross section of every turn is 0.00314 cm/sup 2/. The rogowski coil registers the current flowing in the tokamak scrape-off-layer (SOL) region and at the edge. The sensitivity of the coil is sufficiently increased in order to observe the current filaments existing in the tokamak SOL and edge region.