Effects of trapped alpha particles on ballooning modes in tokamaks

Technical Report · Mon Jul 01 04:00:00 EDT 1985

DOI:https://doi.org/10.2172/5510357· OSTI ID:5510357

Spong, D. A.; Sigmar, D. J.; Cooper, W. A.; Hastings, D. E.; Tsang, K. T.

The effects of a trapped, precessing alpha particle population on ballooning modes are examined for a large-aspect-ratio, shifted circular flux surface tokamak equilibrium. The alphas are modeled in the deeply trapped limit and with a Maxwellian distribution in energy. The resulting kinetic ballooning equation is solved numerically, and the dependence of the eigenvalues and stability boundaries on shear, background pressure gradient, and ratio of hot to background temperatures and densities is investigated. In the low-frequency regime (..omega.. << ..omega../sub dH/ = alpha precessional drift frequency), the alpha component has a stabilizing influence, while in the intermediate-frequency range (..omega.. less than or equal to ..omega../sub dH/) the alphas destabilize ballooning modes through interaction with the trapped particle precessional drift resonance. Parameter ranges that should be typical of alpha production in near-term tokamak devices such as the Tokamak Fusion Test Reactor (TFTR) are considered.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5510357
• Report Number(s): ORNL/TM-9598; ON: DE85015064
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
ALPHA PARTICLES
ASPECT RATIO
BALLOONING INSTABILITY
CHARGED PARTICLES
CLOSED PLASMA DEVICES
INSTABILITY
MAGNETIC FLUX
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
TFTR TOKAMAK
THERMONUCLEAR DEVICES
THERMONUCLEAR REACTORS
TOKAMAK DEVICES
TOKAMAK TYPE REACTORS
TRAPPED-PARTICLE INSTABILITY