Resonant plasma heating below the cyclotron frequency

White, R. B.; Chen, Liu; Lin, Zhihong

doi:10.1063/1.1445180

Cited by 80 publications

(65 citation statements)

References 7 publications

(4 reference statements)

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“…Second, we confirmed the result of Ref. 9 that the stochasticity threshold can be strongly reduced (by several orders of magnitude) in the presence of many waves, ω n with n = 1, 2, 3...n max 1. However, we found that this will be the case only when ∆ω ≡ |ω n+1 − ω n | ω n , the heating efficiency growing with (∆ω) −1 .…”

Section: Discussionsupporting

confidence: 76%

Ion acceleration in plasmas with Alfvén waves

2005

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Effects of elliptically polarized Alfvén waves on thermal ions are investigated. Both regular oscillations and stochastic motion of the particles are observed. It is found that during regular oscillations the energy of the thermal ions can reach magnitudes well exceeding the plasma temperature, the effect being largest in low-β plasmas (β is the ratio of the plasma pressure to the magnetic field pressure). Conditions of a low stochasticity threshold are obtained. It is shown that stochasticity can arise even for waves propagating along the magnetic field provided that the frequency spectrum is non-monochromatic. The analysis carried out is based on equations derived by using a Lagrangian formalism. A code solving these equations is developed. Steady-state perturbations and perturbations with the amplitude slowly varying in time are considered.

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Section: Discussionsupporting

confidence: 76%

Ion acceleration in plasmas with Alfvén waves

2005

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“…Guo et al (2008) further pointed out that the ion heating occurs when the cyclotron resonances at subcyclotron frequencies start to overlap with their corresponding neighboring resonances and then leads to global stochasticity. When a spectrum of Alfvén waves is considered, White et al (2002) demonstrated that the amplitude threshold of the Alfvén waves for ion stochastic heating can be significantly decreased. Evidences of ion heating by low-frequency Alfvén waves have also been found in laboratory experiments (Gates et al 2001;Fredrickson et al 2002;Zhang et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Ion Heating by a Spectrum of Obliquely Propagating Low-Frequency Alfvén Waves

Chen

2009

ApJ

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Ion stochastic heating by a monochromatic Alfvén wave, which propagates obliquely to the background magnetic field, has been studied by Chen et al. It is shown that ions can be resonantly heated at frequencies a fraction of the ion cyclotron frequency when the wave amplitude is sufficiently large. In this paper, the monochromatic wave is extended to a spectrum of left-hand polarized Alfvén waves. When the amplitude of the waves is small, the components of the ion velocity have several distinct frequencies, and their motions are quasi-periodic. However, when the amplitude of the waves is sufficiently large, the components of the ion velocity have a spectrum of continuous frequencies near the ion cyclotron frequency due to the nonlinear coupling between the Alfvén waves and the ion gyromotion, and the ion motions are stochastic. Compared with the case of a monochromatic Alfvén wave, the threshold of the ion stochastic heating by a spectrum of Alfvén waves is much lower. Even when their frequencies are only several percent of the ion cyclotron frequency, the ions can also be stochastically heated. The relevance of this heating mechanism to solar corona is also discussed.

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“…It is interesting to note the analogy between the fractional resonances and resonant heating below the cyclotron frequency as described in Refs. [9,10]. In the cyclotron case the heating, W c ¼ v ?…”

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confidence: 99%

Fractional Resonances between Waves and Energetic Particles in Tokamak Plasmas

et al. 2012

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From numerical simulation and analytical modeling it is shown that fast ions can resonate with plasma waves at fractional values of the particle drift-orbit transit frequency when the plasma wave amplitude is sufficiently large. The fractional resonances, which are caused by a nonlinear interaction between the particle orbit and the wave, give rise to an increased density of resonances in phase space which reduces the threshold for stochastic transport. The effects of the fractional resonances on spatial and energy transport are illustrated for an energetic particle geodesic acoustic mode but they apply equally well to other types of MHD activity.

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Resonant plasma heating below the cyclotron frequency

Cited by 80 publications

References 7 publications

Ion acceleration in plasmas with Alfvén waves

Ion acceleration in plasmas with Alfvén waves

Ion Heating by a Spectrum of Obliquely Propagating Low-Frequency Alfvén Waves

Fractional Resonances between Waves and Energetic Particles in Tokamak Plasmas

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