TY - JOUR
T1 - Effects of toroidal field ripple on suprathermal ions in tokamak plasmas
AU - Goldston, Robert James
AU - Towner, H. H.
N1 - Funding Information:
The authors would like to thank Dr Paul Rutherford for his continued encouragement and interest in this problem. We would also like to thank Dr Rutherford and Dr Allen Boozer for a number of enlightening discussions on the subject of collisionless ripple-trapping and banana-drift diffusion. Similarly, we acknowledge very helpful conversations with Dr David Mikkelsen on the question of residence time in the ripple wells. Finally we are especially grateful to Dr Marshall Rosenbluth for his elegant analytic solutions for Nn and Nn(p) using Wiener-Hopf techniques. This work was supported by U.S. Department of Energy Contract No. EY-7G-C-02-3073.
PY - 1981/10
Y1 - 1981/10
N2 - Analytic calculations of three important effects of toroidal field ripple on suprathermal ions in tokamak plasmas are presented. In the first process, collisional ripple-trapping, ions become trapped in local magnetic wells near their banana tips owing to pitch-angle scattering as they traverse the ripple on barely unripple-trapped orbits. In the second process, collisionless ripple-trapping, ions are captured (again near a banana tip) owing to their finite orbits, which carry them out into regions of higher ripple. In the third process, banana-drift diffusion, fast-ion banana orbits fail to close precisely, due to a ripple-induced ‘e lingering period ’e banana tips. These three mechanisms lead to substantial radial transport of banana-trapped, neutral-beam-injected ions when the quantity a*n O/Nqsis of order unity or smaller.
AB - Analytic calculations of three important effects of toroidal field ripple on suprathermal ions in tokamak plasmas are presented. In the first process, collisional ripple-trapping, ions become trapped in local magnetic wells near their banana tips owing to pitch-angle scattering as they traverse the ripple on barely unripple-trapped orbits. In the second process, collisionless ripple-trapping, ions are captured (again near a banana tip) owing to their finite orbits, which carry them out into regions of higher ripple. In the third process, banana-drift diffusion, fast-ion banana orbits fail to close precisely, due to a ripple-induced ‘e lingering period ’e banana tips. These three mechanisms lead to substantial radial transport of banana-trapped, neutral-beam-injected ions when the quantity a*n O/Nqsis of order unity or smaller.
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U2 - 10.1017/S0022377800010680
DO - 10.1017/S0022377800010680
M3 - Article
AN - SCOPUS:0019624241
SN - 0022-3778
VL - 26
SP - 283
EP - 307
JO - Journal of Plasma Physics
JF - Journal of Plasma Physics
IS - 2
ER -