共查询到20条相似文献,搜索用时 15 毫秒
1.
Ion heating and high-energy-particle production by ion-cyclotron heating in the large helical device
Mutoh T Kumazawa R Seki T Watari T Saito K Torii Y Hartmann DA Zhao Y Sasao M Isobe M Osakabe M Krasilnikov AV Ozaki T Narihara K Nagayama Y Inagaki S Shimpo F Nomura G Yokota M Akaishi K Ashikawa N de Vries P Emoto M Funaba H Fukuyama A Goto M 《Physical review letters》2000,85(21):4530-4533
Ion-cyclotron heating was applied to the Large Helical Device. When the proton-cyclotron resonance was near the saddle point of the magnetic field-strength plane, strong ion-cyclotron damping occurred. Under these conditions efficient plasma heating was achieved for more than one minute. A high-energy ion tail was observed, and the effective tail temperature was determined by a balance between the wave acceleration and the electron-drag relaxation. There was no apparent sign of particle orbit loss effect in the investigated density range of 0.8-1.3x10(19) m(-3). 相似文献
2.
The trajectories of ions confined in a field-reversed configuration (FRC) equilibrium magnetic geometry and heated with a small-amplitude, odd-parity rotating magnetic field (RMF) have been studied with a Hamiltonian computer code. When the RMF frequency is in the ion-cyclotron range, explosive heating occurs. Higher-energy ions are found to have betatron-type orbits, preferentially localized near the FRC's midplane. These results are relevant to a compact magnetic-fusion-reactor design. 相似文献
3.
The high-energy tail of the ion energy distribution is heated by an instability with broad-band frequency spectrum having a peak a little above the ion-cyclotron frequency. The tail heating of the ions is enhanced under a mirror configuration of the magnetic field. 相似文献
4.
T. Tetsuka K. Kawahata A. Nishizawa J. Fujita S. Okajima 《International Journal of Infrared and Millimeter Waves》1985,6(8):729-739
Observation of density fluctuations in tokamak plasmas is important to study the plasma confinement and to perform high power heating of the plasma. We observed the density fluctuations by means of an HCN laser scattering method during rf heating in the ion-cyclotron range of frequency on a tokamak plasma.The density fluctuations at the drift wave frequency are not enhanced so much by the heating, but the frequency spectrum is shifted to higher frequency. The increase of the density fluctuation level during the heating has been observed only in low-frequency region owing to MHD activity. 相似文献
5.
Wave trajectories in high density tokamak plasmas are studied numerically. Results show that the ordinary wave injected at an appropriate incident angle can propagate into the dense plasmas and is mode-converted to the extraordinary wave at the plasma cutoff, is further converted to the electron Bernstein wave during passing a loop or a folded curve near the upper hybrid resonance (UHR) layer, and is cyclotron damped away, resulting in local electron heating before arriving at the cyclotron resonance layer. Similar trajectory and damping are obtained when a microwave in a form of extraordinary wave is injected quasi-perpendicularly in the direction of decreasing toroidal field. 相似文献
6.
Cottrell GA 《Physical review letters》2000,84(11):2397-2400
First measurements and identification of minority ion-cyclotron emission (MICE) during ICRF (H)D minority heating in the JET tokamak are presented. An inner wall radiofrequency (rf) probe shows the new single MICE spectral line, down-shifted from the heating frequency and appearing approximately 400 ms after the ICRH switch-on. The line is narrow (Deltaomega/omega approximately 0.04), characterized by the ion-cyclotron frequency of minority protons in the outer-edge midplane plasma and is observed irrespective of whether single or multifrequency ICRH is applied. The observations are consistent with the classical evolution and population of the plasma edge with approximately 3 MeV ICRH protons on orbits near the outboard limiters. Particle loss and energy filtering contribute to a local non-Maxwellian energetic ion distribution, which is susceptible to ion-cyclotron instability. 相似文献
7.
The dispersion relation for electrostatic ion-cyclotron (EIC) waves in a plasma containing a fraction of negative ions is derived from the fluid picture. Two wave modes are generally possible. Some of their features are investigated. 相似文献
8.
介绍了离子回旋波加热领域研究进展,具体分析了快波少子加热模式转换情况以及影响模式转换分量大小和位置的因素。通过控制波的频率及少子浓度,使得波能够顺利传播到托卡马克等离子体的离子混合共振与截止的区域附近,并转换为离子Bernstein波而被等离子体有效吸收,因而能够改善加热效果。 相似文献
9.
The resonant absorption of a plasma surface wave is supposed to be an important and efficient mechanism of power deposition for a surface wave plasma source. In this paper, by using the particle-in-cell method and Monte Carlo simulation, the resonance absorption mechanism is investigated. Simulation results demonstrate the existence of surface wave resonance and show the high efficiency of heating electrons. The positions of resonant points, the resonance width and the spatio-temporal evolution of the resonant electric field are presented, which accord well with the theoretical results. The paper also discusses the effect of pressure on the resonance electric field and the plasma density. 相似文献
10.
The experimental conditions that facilitate the excitation of parametric decay instabilities upon the electron cyclotron resonance heating of a plasma at the second harmonic extraordinary wave in tokamaks and stellarators and, as a result, make anomalous absorption of microwave power possible have been analyzed. It has been shown that, in the case of a nonmonotonic radial profile of the plasma density, when the beam of electron cyclotron waves passes near the equatorial plane of a toroidal device, the parametric excitation of electron Bernstein waves, as well as the generation of ion Bernstein waves propagating from the parametric decay region to the nearest ion cyclotron harmonic, where they efficiently interact with ions, is possible. The proposed theoretical model can explain the anomalous generation of accelerated ions observed upon electron cyclotron heating in small and moderate toroidal facilities. 相似文献
11.
A right-hand circularly polarized (RHCP) electron cyclotron wave is launched along the axis of a steady-state magnetically confined plasma column. Detailed measurements of the spatial variation of electron temperature, density, plasma potential, and wave amplitude about the resonance zone are presented. In particular, data are presented where the temperature increase due to electron cyclotron resonance heating (ECRH) is strongly localized near the resonance position. A numerical wave heating model has been developed for electrons in a magnetic mirror and is found to be in qualitative agreement with observations. 相似文献
12.
Nelson-Melby E Porkolab M Bonoli PT Lin Y Mazurenko A Wukitch SJ 《Physical review letters》2003,90(15):155004
The process of mode conversion, whereby an externally launched electromagnetic wave converts into a shorter wavelength mode(s) in a thermal plasma near a resonance in the index of refraction, is particularly important in a multi-ion species plasma near the ion cyclotron frequency. Using phase contrast imaging techniques (PCI), mode-converted electromagnetic ion cyclotron waves have been detected for the first time in the Alcator C-Mod tokamak near the H-3He ion-ion hybrid resonance region during high power rf heating experiments. The results agree with theoretical predictions. 相似文献
13.
Low-frequency noise (fci < f < fpi) excited by positively biased probes of various diameters near the magnets in a multidipole plasma device is investigated. It is concluded that the noise is due to the excitation of oblique ion-acoustic waves, i.e., the electrostatic ion-cyclotron waves in the low field limit propagating at large angles to the magnetic field. 相似文献
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16.
<正>Ion pickup by a monochromatic low-frequency Alfven wave,which propagates along the background magnetic field,has recently been investigated in a low beta plasma(Lu and Li 2007 Phys.Plasmas 14 042303).In this paper, the monochromatic Alfven wave is generalized to a spectrum of Alfven waves with random phase.It finds that the process of ion pickup can be divided into two stages.First,ions are picked up in the transverse direction,and then phase difference(randomization) between ions due to their different parallel thermal motions leads to heating of the ions.The heating is dominant in the direction perpendicular to the background magnetic field.The temperatures of the ions at the asymptotic stage do not depend on individual waves in the spectrum,but are determined by the total amplitude of the waves.The effect of the initial ion bulk flow in the parallel direction on the heating is also considered in this paper. 相似文献
17.
A dispersion relation for low-frequency electrostatic modes in a plasma with negative ions is derived for the case in which a velocity shear Kelvin-Helmholtz instability exists in the positive ion flow along the magnetic field. It is found that the negative ions have, generally, a destabilizing effect, as seen previously for ion-acoustic and electrostatic ion-cyclotron waves. The influence of the negative-ion-to-positive-ion mass mass ratio on the stability is also examined 相似文献
18.
T. Cho S. Kubo M. Ikeda M. Nakamura Y. Terumichi Y. Hamada S. Tanaka 《Physics letters. A》1980,80(4):269-272
When a high power microwave is injected into a tokamak plasma, the intensities of microwave radiations emitted from the plasma and those of impurity lines are increased. Such increases are observed only when the electron cyclotron resonance field is present in the torus. The upper hybrid resonance heating is also observed near the plasma surface. 相似文献
19.
Ion pickup by a monochromatic low-frequency Alfvén wave, which
propagates along the background magnetic field, has recently been
investigated in a low beta plasma (Lu and Li 2007 Phys.
Plasmas 14 042303). In this paper, the monochromatic Alfvén
wave is generalized to a spectrum of Alfvén waves with random
phase. It finds that the process of ion pickup can be divided into
two stages. First, ions are picked up in the transverse direction,
and then phase difference (randomization) between ions due to their
different parallel thermal motions leads to heating of the ions. The
heating is dominant in the direction perpendicular to the background
magnetic field. The temperatures of the ions at the asymptotic stage do
not depend on individual waves in the spectrum, but are determined
by the total amplitude of the waves. The effect of the initial ion
bulk flow in the parallel direction on the heating is also
considered in this paper. 相似文献
20.
Jaeger EF Berry LA Myra JR Batchelor DB D'Azevedo E Bonoli PT Phillips CK Smithe DN D'Ippolito DA Carter MD Dumont RJ Wright JC Harvey RW 《Physical review letters》2003,90(19):195001
A two-dimensional integral full-wave model is used to calculate poloidal forces driven by mode conversion in tokamak plasmas. In the presence of a poloidal magnetic field, mode conversion near the ion-ion hybrid resonance is dominated by a transition from the fast magnetosonic wave to the slow ion cyclotron wave. The poloidal field generates strong variations in the parallel wave spectrum that cause wave damping in a narrow layer near the mode conversion surface. The resulting poloidal forces in this layer drive sheared poloidal flows comparable to those in direct launch ion Bernstein wave experiments. 相似文献