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Title: Particle simulations of mode conversion between slow mode and fast mode in lower hybrid range of frequencies

The propagation and mode conversion of lower hybrid waves in an inhomogeneous plasma are investigated by using the nonlinear δf algorithm in a two-dimensional particle-in-cell simulation code based on the gyrokinetic electron and fully kinetic ion (GeFi) scheme [Lin et al., Plasma Phys. Controlled Fusion 47, 657 (2005)]. The characteristics of the simulated waves, such as wavelength, frequency, phase, and group velocities, agree well with the linear theoretical analysis. It is shown that a significant reflection component emerges in the conversion process between the slow mode and the fast mode when the scale length of the density variation is comparable to the local wavelength. The dependences of the reflection coefficient on the scale length of the density variation are compared with the results based on the linear full wave model for cold plasmas. It is indicated that the mode conversion for the waves with a frequency of 2.45 GHz (ω ∼ 3ω{sub LH}, where ω{sub LH} represents the lower hybrid resonance) and within Tokamak relevant amplitudes can be well described in the linear scheme. As the frequency decreases, the modification due to the nonlinear term becomes important. For the low-frequency waves (ω ∼ 1.3ω{sub LH}), the generations of the high harmonic modes and sidebandsmore » through nonlinear mode-mode coupling provide new power channels and thus could reduce the reflection significantly.« less
Authors:
; ;  [1] ;  [2] ;  [1] ;  [3] ;  [4]
  1. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)
  2. (China)
  3. (United States)
  4. Physics Department, 206 Allison Laboratory, Auburn University, Alabama 36849-5311 (United States)
Publication Date:
OSTI Identifier:
22493814
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 1; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALGORITHMS; AMPLITUDES; COLD PLASMA; COMPUTERIZED SIMULATION; ELECTRONS; GHZ RANGE; INHOMOGENEOUS PLASMA; IONS; LOWER HYBRID HEATING; MODE CONVERSION; NONLINEAR PROBLEMS; REFLECTION; RESONANCE; TOKAMAK DEVICES; TWO-DIMENSIONAL CALCULATIONS