Designing a VH-mode core/L-mode edge discharge
- General Atomics, San Diego, CA (United States)
- Univ. of Texas, Austin, TX (United States). Fusion Research Center
An operating mode with a very high confinement core like the VH-mode but a very low power flow to the divertor plates and low edge particle confinement like an L-mode would be beneficial. For a large tokamak like the proposed ITER, the power density at the separatrix is not that far above the scaled H-mode power threshold so not much of the power can be radiated inside of the separatrix without causing a return to L-mode. The thicker scrape-off layer of an L-mode increases the radiating volume of the scrape-off layer and helps shield impurities from the core. This is especially important if the first wall is metallic. In this paper an H-mode transport model based on E x B velocity shear suppression of turbulence will be used to show that it is possible to have a strongly radiating mantle near the separatrix, which keeps the edge in L-mode, while having a VH-mode core with a broad region of suppressed turbulence. The existing results of enhanced L-mode confinement during impurity injection on a number of tokamaks will be surveyed. The operating conditions which will most likely result in the further improvement of the core confinement by control of the heating, fueling, and torque profiles will be identified.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-89ER51114
- OSTI ID:
- 195708
- Report Number(s):
- GA--A22155; CONF-9509238--3; ON: DE96005248
- Country of Publication:
- United States
- Language:
- English
Similar Records
Impurity penetration and transport during VH-mode on DIII-D
The role of the radial electric field in confinement and transport in H-mode and VH-mode discharges in the DIII-D tokamak