Numerical simulations of resistive magnetohydrodynamic instabilities in a poloidal divertor tokamak

Technical Report · Tue Mar 01 04:00:00 EST 1988

OSTI ID:7171490

Uchimoto, E

A new 3-D resistive MHD initial value code RPD has been successfully developed from scratch to study the linear and nonlinear evolution of long wavelength resistive MHD instabilities in a square cross-section tokamak with or without a poloidal divertor. The code numerically advances the full set of compressible resistive MHD equations in a toroidal geometry, with an important option of permitting the divertor separatrix and the region outside it to be in the computational domain. A severe temporal step size restriction for numerical stability imposed by the fast compressional waves was removed by developing and implementing a new, efficient semi-implicit scheme extending one first proposed by Harned and Kerner. As a result, the code typically runs faster than that with a mostly explicit scheme by a factor of about the aspect ratio. The equilibrium input for RPD is generated by a new 2-D code EQPD that is based on the Chodura-Schluter method. The RPD code, as well as the new semi-implicit scheme, has passed very extensive numerical tests in both divertor and divertorless geometries. Linear and nonlinear simulations in a divertorless geometry have reproduced the standard, previously known results. In a geometry with a four-node divertor the m = 2,n = 1 (2/1) tearing mode tends to be linearly stabilized as the q = 2 surface approaches the divertor separatrix. However, the m = 1,n = 1 (1/1) resistive kink mode remains relatively unaffected by the nearness of the q = 1 surface to the divertor separatrix. When plasma current is added to the region outside the divertor separatrix, the 2/1 tearing mode is linearly stabilized not by this current, but by the profile modifications induced near the q = 2 surface and the divertor separatrix. A similar stabilization effect is seen for the 1/1 resistive kink mode, but to a lesser extent. 77 refs., 91 figs.

• Research Organization: Wisconsin Univ., Madison (USA)
• DOE Contract Number: FG02-86ER53218
• OSTI ID: 7171490
• Report Number(s): DOE/ER/53218-120; ON: DE88010768
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
ANNULAR SPACE
COMPUTER CODES
CONFIGURATION
DIVERTORS
INSTABILITY
KINK INSTABILITY
MATHEMATICS
NUMERICAL ANALYSIS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA SIMULATION
POLOIDAL FIELD DIVERTORS
R CODES
SIMULATION
SPACE
THERMONUCLEAR REACTORS
THREE-DIMENSIONAL CALCULATIONS
TOKAMAK TYPE REACTORS
TOROIDAL CONFIGURATION