Main divertor flows in Heliotron E: their distribution and dependence on NBI and ECH

In the l = 2/m = 19 Heliotron E heliotron/torsatron device, with a currentl ess plasma heated by NBI and ECH, the poloidal distributions were measured of diverted plasma flows near the vacuum chamber wall in eight sections of one helical field pitch. A vertical asymmetry of these distributions was ob served, contrary to what had been expected from the helical symmetry of the 'ideal' (unperturbed) vacuum divertor magnetic configuration. Under NBI co nditions, the density normalized divertor plasma flow J(d)/(n) over bar(e) was a rising function of the density normalized absorbed power P-abs/(n) ov er bar(e). This is considered to be a consequence of the power degradation of confinement. With second harmonic ECH, where the main part of the launch ed power was absorbed in the central region, a similar power dependence as for the NBI was observed. With fundamental ECH, where a considerable fracti on of the microwave power was absorbed at the periphery, J(d)/(n) over bar( e) for some areas of the divertor trace distinctly exceeded those obtained under NBI-only conditions with the same P-abs/(n) over bar(e). On the other hand, two different time responses (fast and slow) of J(d) Were observed f or the perpendicular NBI and fundamental ECH cases in some particular posit ions. The slow response is considered to be caused by a diffusion-like outf low of the bulk plasma to the divertor. The fast outflow of particles to th e divertor might be caused by a loss of locally trapped high energy electro ns and ions.