Studies in JET divertors of varied geometry I: Non seeded plasma operation
Results of experiments investigating the performance of the Joint European Torus (JET) Mark IIA divertor are reported and compared to the performance of its Mark I predecessor. The principal effect of reducing the divertor width (increasing closure) was to increase pumping for both deuterium and impurities while reducing upstream neutral pressure. Neither the orientation of the divertor target relative to the divertor plasma nor the width of the divertor had a major influence on core plasma performance in ELMy H-modes. Changing the core triangularity and thus the edge magnetic shear modifies the edge-localized mode (ELM) frequency in ELMy H-mode plasmas thereby changing the peak divertor power loading. The integrated performance of the core and divertor plasmas is reviewed with a view to extrapolation to the requirements of the international thermonuclear experimental reactor (ITER). The confinement of JET ELMy H-modes with hot, medium density edges is good and follows gyro-Bohm scaling. The impurity content of these discharges is low and within the ITER requirements. When one attempts to raise the density with deuterium gas fuelling the ELM frequency increases and the confinement, especially in the edge, decreases.
Bibliographic Reference: Report: JET-P(98)19 EN (1998) 15pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (GB)
Record Number: 199811101 / Last updated on: 1998-10-13
Original language: en
Available languages: en