Effect of detrapping on trapped-particle instabilities in tokamaks

Technical Report · Fri Jan 01 04:00:00 EST 1971

OSTI ID:5957003

Jablon, C J; Rutherford, P H

The effect of weak detrapping of magnetically trapped particles on low-frequency, trapped-particle modes in sheared magnetic configurations is considered; such detrapping can be imposed by oscillation of the magnetic configuration - e.g., by major-radius compression. Detrapping has a dynamical effect analogous to collisions. In particular, it is shown that trapped-particle instabilities in tokamaks can be dynamically stabilized by weak oscillation of the aspect ratio with frequency ..cap omega.. and relative amplitude lambda, thus imitating ion collisions with ion detrapping. In the intermediate regime of the collisional trapped-particle instability, where nu/sub i//epsilon << ..omega.. approx. epsilon/sup 1/2/ ..omega..* << nu/sub e//epsilon, stabilization is found if ..omega.. << ..cap omega.. < lambda nu/sub e//epsilon, where epsilon = r/R. The stabilizing effect (surprisingly of order lambda) arises from oscillation of the field strength near its maximum, where detrapping occurs. These results are for simple models of the geometry. 8 refs.

• Research Organization: Princeton Univ., NJ (USA). Plasma Physics Lab.
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5957003
• Report Number(s): MATT-823; ON: DE88002017
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
ASPECT RATIO
BOLTZMANN-VLASOV EQUATION
CLOSED PLASMA DEVICES
DIFFERENTIAL EQUATIONS
DISPERSION RELATIONS
ELECTRIC POTENTIAL
EQUATIONS
INSTABILITY
KINETIC EQUATIONS
MAGNETIC FIELD CONFIGURATIONS
PARTIAL DIFFERENTIAL EQUATIONS
PERTURBATION THEORY
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TRAPPED-PARTICLE INSTABILITY