Characteristics of the scrape-off layer in DIII-D high-performance negative central magnetic shear discharges
- Lawrence Livermore National Lab., CA (United States)
- Oak Ridge Associated Universities, TN (United States)
- General Atomics, San Diego, CA (United States); and others
In this paper the authors present measurements of the global power and particle balance in the high-performance phase of negative central magnetic shear (NCS) discharges and compare with reference VH-mode discharges. The principal differences observed are that NCS has a much lower fraction of the total input power flowing into the boundary, less core radiation, and larger rate of stored energy increase as a fraction of total power. Scrape-off layer (SOL) temperature and divertor heat flux profiles, and radiation profiles at the midplane, are similar to VH-mode. Due to the good core particle confinement and efficient fueling by neutral beam injection (NBI), with little gas puffing, the gas load on the walls and the recycling are very low during the NCS discharges. This results in a rate of density rise relative to beam fueling at the L to H transition time which is 1/3 of the value for VH transitions, which is in turn 1/2 that for L-to-ELMing-H-mode transitions.
- Research Organization:
- General Atomics, San Diego, CA (United States); Oak Ridge National Lab., TN (United States); Sandia National Labs., Albuquerque, NM (United States); California Univ., San Diego, La Jolla, CA (United States); Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC03-89ER51114; AC05-96OR22464; AC04-94AL85000; FG03-95ER54294; W-7405-ENG-48
- OSTI ID:
- 453511
- Report Number(s):
- GA--A22353; UCRL-JC--125490; CONF-960569--18; ON: DE97004330
- Country of Publication:
- United States
- Language:
- English
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