MEASUREMENTS OF PLASMA-BETA IN STELLARATORS

Measurements are reported of the average plasma beta of ECRH plasmas i n the TJ-IU torsatron using external flux loops. The method is based o n measurements of the magnetic flux produced by the Pfirsch-Schluter c urrent due to the plasma pressure. The most important advantages of us ing this method over the conventional diamagnetic method are much high er relative signal ratio (useful signal owing to plasma beta over the total background signal) and easy installation of the diagnostic in an y type of stellarator device. A general description of the technique a nd its applications to more complicated stellarator devices like TJ-II is also presented.