Stabilization of collisional drift-tearing modes at the breakdown of the constant-. Psi. approximation

Journal Article · Sat Jun 01 00:00:00 EDT 1991 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859828· OSTI ID:5793742

Migliuolo, S; Pegoraro, F; Porcelli, F ^[1]

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1. JET Joint Undertaking, Abingdon, Oxon OX14 3EA, England (GB)

The linear growth rate of the collisional drift-tearing mode is found to be a nonmonotonic function of the stability parameter {Delta}{prime}. It reaches a maximum for {Delta}{prime}{approx}0.5{Delta}{sup {prime}}{sub 1}={ital m}{omega}{sub A}/ {radical}{cflx {omega}}{sub *{ital e}}({cflx {omega}}{sub *{ital e}}{minus}{omega}{sub {ital di}}) {gt} 0, where {omega}{sub A}, {cflx {omega}}{sub *{ital e}}, {omega}{sub {ital di}} are the Alfven, electron drift wave, and ion diamagnetic frequencies, and becomes negative for {Delta}{prime} {ge} {Delta}{sup {prime}}{sub 1}, corresponding to the regime where the constant-{Psi} approximation breaks down. A second mode, identified as the diamagnetic modification of the {epsilon}{sup 1/3}{sub {eta}} mode near the condition for ideal magnetohydrodynamic (MHD) marginal stability, becomes unstable for {Delta}{prime}{ge}{Delta}{sup {prime}}{sub 2} = ({cflx {omega}}{sub *{ital e}}/{omega}{sub A}{epsilon}{sub {eta}}){sup 1/2} {gt} {Delta}{sup {prime}}{sub 1}, leaving a stable window in values of {Delta}{prime}. Applications to the stability of modes with poloidal and toroidal mode numbers {ital m} = {ital n} = 1 are presented.

• DOE Contract Number: AC02-78ET51013
• OSTI ID: 5793742
• Journal Information: Physics of Fluids B; (USA), Vol. 3:6; ISSN 0899-8221
• Country of Publication: United States
• Language: English

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY
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INSTABILITY GROWTH RATES
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