ENERGY AND PARTICLE CONFINEMENT IN WENDELSTEIN VII-A - ECRH PLASMA
In the ECRH experiments on W VII-A OH-currentfree stellarator plasmas were produced which are well in the LMFP regime. Plasma confinement at these conditions of low collisionality has been analyzed by modelling the measured temperature and density profiles by 1-D transport calculations. As a result of numerical transport analysis the radial energy transport of the ECRH plasma could be described by: axisymmetric neoclassical transport in the central region, neoclassical losses (helical ripple at LMFP conditions) in the intermediate zone, and anomalous loss dominating in the edge region. The measured density profiles could be modelled with a diffusion coefficient D(an) approximately equal 1/15Xe(an) and an atomic particle influx at the plasma boundary. However, an ALCATOR-like scaling would also allow a reasonable data fit. More conclusive results can be expected from future experiments (70 GHz ECRH on W VII-A and W VII-AS). At specific conditions (very peaked temperature profile and high density), stationary hollow density profiles were observed. Numerical calculations showed that the density depression in the plasma body should be even more pronounced at higher densities and larger dimensions in the future W VII-AS experiment (reduction of the particle source term).
Bibliographic Reference: 5TH INTERNATIONAL WORKSHOP ON STELLARATORS, SCHLOSS RINGBERG, BAVARIA (GERMANY), SEPT. 24-28, 1984 VOL. I, PP. 233-243, EUR 9618 EN (1985) FS, VOL. I AND VOL. II, 787 P., BFR 3500 (BOTH VOLUMES), EUROFFICE, LUXEMBOURG, POB 1003
Record Number: 1989124119700 / Last updated on: 1987-01-01
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