Year: 1993
Type: article
Abstract: The density limits were determined in Ohmic and L mode discharges over a wide range of parameters: B T = 0.8-2.1 T, I p = 0.5-1.9 MA, an elongation of 1.09 to 1.92, Z eff < 2, P beam ≲ 8 MW and n e,max 1.2 × 10 20 m -3 . The density limits in ELMing H mode discharges were also determined and found to be comparable with those of the Ohmic and L mode discharges. In Ohmic plasmas, the density limit increased linearly with I p and decreased with minor radius (~1/a 2.4 ); the density limit showed little, if any, dependence on either B T or plasma elongation. These results are in good qualitative agreement with Greenwald density limit scaling, (n e,max (10 20 m -3 ) ~ I p (MA)/a 2 (m)). In discussing the density limits of detached plasmas, the 'effective' minor radius must be considered. The density limit data for L and H mode discharges were also consistent with Greenwald scaling. The density limits in the L and H modes were insensitive to the heating power. In the Ohmic and L mode cases, rotating MHD modes, typically with m/n=2/1, existed in high density discharges with no perceptible adverse impact on particle confinement until they locked, precipitating global disruptive behaviour. To date, the data show that the ELMing H mode density limit is not disruptive in itself
Source: Nuclear Fusion
Authors: T.W Petrie, A.G Kellman, M.A Mahdavi
Institution: General Atomics (United States)
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Award: G1398330795
OpenAlex ID: W2045772489