STATUS OF WENDELSTEIN VII-A
The investigations concern transport, heating and stability of currentless plasma. The plasma behaviour is strongly influenced by the rotational transform t. At t = m/n; m, n = 1,2,... so far beta proportional to the input power has been demonstrated. Up to beta(o) = 1 % no MHD instabilities have been observed. Deterioration of confinement at t = m/n is rather an effect if island formation and convection at resonant surfaces. During NI almost classical collisional slowing down has been verified analyzing the neutron production rate and charge exchange fluxes for modulating power. The measured high ion temperatures appear feasible, if the ion heat conduction is less than predicted by neoclassical theory. All ablation experiments to study impurity transport were in reasonable agreement with neoclassical predictions. Irradiating the plasma with the ordinary wave (TE-11, HE-11 mode) by the concentrated power deposition electron temperatures T-e <= 10**13 cm**-3 could be obtained for ECRH at 1 T main field. Changing the magnetic field, major variations of the T-e profiles can be realized. The electron heat transport in the inner part of the plasma agrees with neoclassical predictions. In a first step applying ICRH (100 kW, 50 MHz) P-IN about 10 kW has been coupled to the plasma. A strong increase of radiative losses (iron, oxygen) has been observed.
Bibliographic Reference: 5TH INTERNATIONAL WORKSHOP ON STELLARATORS, SCHLOSS RINGBERG, BAVARIA (GERMANY) SEPT. 24-28, 1984 VOL. I, PP. 79-109, EUR 9618 EN (1985) FS, VOL. I AND VOL. II, 787 P., BFR 3500 (BOTH VOLUMES), EUROFFICE, LUXEMBOURG, POB 1003
Record Number: 1989124115600 / Last updated on: 1987-01-01
Available languages: en