Nonlinear mode conversion and anomalous absorption processes during radio-frequency heating of bumpy torus plasmas

Ştefan, V.; Krall, Nicholas A.

doi:10.1063/1.865134

Cited by 15 publications

(11 citation statements)

References 43 publications

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“…Stefan and Bers (1984) surveyed parametric instabilities associated with electron cyclotron heating that lead to nonlinear absorption; they analyzed a dispersion relation for finite-wave-number ordinary and extraordinary pump waves which decay into electrostatic waves and were particularly interested in the secondary decay instabilities of the parametrically destabilized electrostatic waves. Stefan and Krall (1985) reviewed nonlinear conversion and parametric absorption of finite-wave number electron cyclotron waves as applied to the heating of bumpy torus plasmas. The secondary parametric decay and possible cascade of the decay products, as well as pump depletion, were among the saturation mechanisms analyzed by Stefan and Krall. The generalization of the dispersion relations describing parametric decays into electrostatic waves to include stimulated scattering has been presented by B.…”

Section: A Parametric Instabilitiesmentioning

confidence: 99%

“…The secondary parametric decay and possible cascade of the decay products, as well as pump depletion, were among the saturation mechanisms analyzed by Stefan and Krall. The generalization of the dispersion relations describing parametric decays into electrostatic waves to include stimulated scattering has been presented by B. Cohen (1987a), Stefan et al (1987), Stenflo (1989, and others. In stimulated scattering, an incident electromagnetic wave can parametrically couple to a scattered electromagnetic wave and another mode that is typically an electrostatic normal mode or quasimode in the plasma.…”

Section: A Parametric Instabilitiesmentioning

confidence: 99%

“…Parametric decay into two upper-hybrid waves or two obliquely propagating, magnetized plasma waves is not included in (4.1), in analogy to the similar observation for an unmagnetized plasma (Drake et al, 1974). Stenflo (1989) showed that Eq. (4.1) can be straightforwardly generalized to include collisions.…”

Section: A Parametric Instabilitiesmentioning

confidence: 99%

“…Although the low microwave powers in DDT restrict the expected beat-wave current drive to have a low efficiency, experiments in DDT should be able to quantitatively test the resonant excitation of beat waves and electron acceleration in a bounded, magnetized plasma. While there have been many experiments preceding DDT that have studied the resonant excitation of beat waves, beat-wave acceleration, and optical mixing (see the review by Stefan, Cohen, and Joshi, 1989, and references therein), the experimental observation of beat-wave current drive in the toroidal geometry of DDT will be significant for future magnetic fusion applications.…”

Section: Experimental Testsmentioning

confidence: 99%

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Theory of free-electron-laser heating and current drive in magnetized plasmas

Cohen

Nevins

et al. 1991

Rev. Mod. Phys.

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The introduction of a powerful new microwave source, the free-electron laser, provides new opportunities for novel heating and current-drive schemes to be used in toroidal fusion devices. This high-power, pulsed source has a number of technical advantages for these applications, and its use is predicted to lead to improved current-drive efficiencies and opacities in reactor-grade fusion plasmas in specific cases. The Microwave Tokamak Experiment at the Lawrence Livermore National Laboratory will provide a test for some of these new heating and current-drive schemes. Although the motivation for much of this research has derived from the application of a free-electron laser to the heating of a tokamak plasma at a frequency near the electron cyclotron frequency, the underlying physics, i.e., the highly nonlinear interaction of an intense, pulsed, coherent electromagnetic wave with an electron in a magnetized plasma including relativistic effects, is of general interest. Other relevant applications include ionospheric modification by radiofrequency waves, high-energy electron accelerators, and the propagation of intense, pulsed electromagnetic waves in space and astrophysical plasmas. This review reports recent theoretical progress in the analysis and computer simulation of the absorption and current drive produced by intense pulses, and of the possible complications that may arise, e.g., parametric instabilities, nonlinear self-focusing, trappedparticle sideband instability, and instabilities of the heated plasma. CONTENTSI. Introduction 949 A. Motivation and scope 949 B. Free-electron laser 950 C. Basic physics 951 D. Outline of succeeding sections 954 II. Wave-Particle Interaction 954 A. Relativistic Hamiltonian and particle dynamics 954 B. Heating and current-drive mechanisms 958 III. Current-Drive Applications 965 A. Pulsed current drive 965 B. Trapped-particle effects 966 C. Current-drive efficiencies 967 IV. Stability of an Intense Electron Cyclotron Wave 971 A. Parametric instabilities 971 B. Trapped-particle sideband instability 974 C. Nonlinear self-focusing 975 D. Stability of the heated plasma 977 V. Simulations of FEL Heating and Current Drive 978 A. Monte Carlo and self-consistent particle simulations 978 B. Nonlinear electron cyclotron heating 978 C. Stochastic heating and current drive 980 D. Rising buckets 981 E. Beat-wave current drive 984 F. Parametric instabilities 985 VI. Experimental Tests 987 VII. Conclusions 987 Acknowledgments 988 References 988

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Section: A Parametric Instabilitiesmentioning

confidence: 99%

Section: A Parametric Instabilitiesmentioning

confidence: 99%

Section: A Parametric Instabilitiesmentioning

confidence: 99%

Section: Experimental Testsmentioning

confidence: 99%

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Theory of free-electron-laser heating and current drive in magnetized plasmas

Cohen

Nevins

et al. 1991

Rev. Mod. Phys.

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“…This area is rich in basic nonlinear plasma phenomena, such as instability saturation, plasma turbulence, and particle acceleration. It's also an area rich in applications, including plasma heating, laser fusion, ionospheric modification, potential accelerators for high-energy physics, and astrophysics [Carlson and Duncan, 1977;Kruer, 1981;Joshi et al, 1984;Stefan and Krall, 1985]. Experiments, theory, and computer simulations have interacted to identify many important basic plasma processes.…”

Section: Introductionmentioning

confidence: 99%

Simulations of electromagnetic wave plasma interactions

Kruer

1990

Radio Science

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The interaction of electromagnetic waves with plasmas is a topic rich in nonlinear effects with applications ranging from laser fusion to space plasmas. Computer simulations are a powerful tool to help understand the growing number of experiments in this area. Here we discuss some simulations of the Raman and two-plasmon decay instabilities and the nonlinear evolution of ponderomotively driven ion acoustic waves. Some salient features are compared with experiments.

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Three-wave coupling coefficient in a drifting bi-Maxwellian plasma

Bergmann

1986

J. Plasma Phys.

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A general electrostatic coupling coefficient which satisfies the Manley-Rowe relations is used to derive an explicit expression for the resonant three-wave coupling coefficient between electrostatic normal modes of a uniformly magnetized, infinite, homogeneous plasma with species described by drifting bi-Maxwellian distribution functions. The limit of this expression is taken when the phase velocities of the three waves are much larger than a species thermal speed, and also when the phase velocities are much smaller than the thermal speed. These are fluid limits and are applicable to the three-wave interaction between some low-frequency electrostatic waves, such as ion acoustic and ion cyclotron modes, in a plasma where Te ≫ Ti.

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Nonlinear mode conversion and anomalous absorption processes during radio-frequency heating of bumpy torus plasmas

Abstract: Articles you may be interested inMonitoring ion current and ion energy during plasma processing using radio-frequency current and voltage measurements AIP Conf.

Cited by 15 publications

References 43 publications

Theory of free-electron-laser heating and current drive in magnetized plasmas

Theory of free-electron-laser heating and current drive in magnetized plasmas

Simulations of electromagnetic wave plasma interactions

Three-wave coupling coefficient in a drifting bi-Maxwellian plasma

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