Observation of Ion Confining Potential Enhancement due to Thermal Barrier Potential Formation and Its Scaling Law in the Tandem Mirror GAMMA 10

Abstract

In the tandem mirror GAMMA 10, (i) the enhancement of the ion confining potential, φ_c, only during the period of the thermal barrier potential φ_b-formation, has been observed first by using not only end-loss-analysers (ELA’s) of GAMMA 10 but an end-loss-ion-spectrometer (ELIS) installed from TMX-U. This results in strong end-loss-ion plugging with increased central cell density. (ii) The first experimental observation of the φ_c vs φ_b-scaling law is obtained, where φ_c increases with φ_b. This scaling law is consistently interpreted by Cohen’s theories of the weak-ECH and the strong-ECH in the plug region, (iii) Good agreement of the plug potential measured with the ELA’s and the ELIS is achieved.