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1.
A dispersion relation has been derived to study the stability of ion cyclotron (IC) propagation at the second harmonic of
the minority component deuterium in a mirror confined plasma that has hydrogen as the majority species. We have worked in
the frame of the majority ions; our dispersion relation can thus be used to study IC propagation in a single ion plasma also.
Analysis of the dispersion relation yields two modes — one below and the other above the ion gyro-frequency ΘH of hydrogen. The expression for the growth rate is used to explicitly show that an instability can arise in the plasma when
the loss-cone indexj⩾3; this instability being a result of the coalescing of the two modes supported by the plasma. Unfortunately, the minority
component deuterium does not decrease this instability and thus the proposed scheme of IC heating at the second harmonic of
the minority component seems unsuited to mirror devices. 相似文献
2.
由相对论回旋动力论方程出发,推导出弱相对论非均匀等离子体的普遍色散关系。该色散关系可以适用于任意的磁场位形和任意有限频率。在色散关系中把带有速度平方项分母的奇异积分用等离子体漂移色散函数解析地表示出来,从而可以把这一结果用于较系统地解析或半解析地研究由弱相对论效应,磁场的梯度和曲率,回旋频移等共振驱动的各种微观不稳定性的性质。由于推导时考虑了温度各向异性的麦氏分布函数,因而可以直接推广并应用到损失锥非平衡分布的情况。文中还演示了它在低杂漂移不稳定性研究中的应用。由该色散关系出发,可以简捷并系统地得到Drake等人的结果。
关键词: 相似文献
3.
Chandu Venugopal 《Pramana》1987,28(2):181-193
A dispersion relation for the near perpendicular propagation of the electromagnetic ion cyclotron wave has been derived in
a fusion plasma that has deuterium as a majority species, hydrogen as a minority species and fully ionized oxygen as an impurity
constituent; all being modelled by loss cone distribution functions. The wave has a frequencyω around the deuterium ion gyrofrequency-ΩD and a wavelength much longer than its Larmor radiusγ
LD(k
⊥
γ
LD<1); the plasma itself being characterized by large ion plasma frequencies (ω
PD
2
>Ω
D
2
). Two modes, a low frequency (LF) and a high frequency (HF) mode of opposite electrical energy can propagate in the plasma;
the instabilities that arise are thus due to an interaction of modes of opposite energies. We find that while hydrogen tends
to destabilize the plasma, the impurity oxygen ions have the reverse effect. Also the plasma is most stable when the ratios
of the perpendicular components of oxygen-to-deuterium and hydrogen-to-deuterium temperatures are kept low. Detailed studies
of the wave propagation characteristics and energy reveal the close resemblance of a loss cone plasma containing oxygen to
a stable Maxwellian plasma in regard to wave stability, propagation and energy. 相似文献
4.
Godfrey Brendan B. Newberger Barry S. Taggart Keith A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1975,3(2):68-75
The dielectric tensor for a multi-component, homogeneous, field-free relativistic plasma is derived in manifestly covariant form. From the dielectric tensor, linear dispersion relations are obtained explicitly when each component of the plasma is isotropic in its rest frame. If the components are relativistic Maxwellians, these dispersion relations are expressible in terms of the relativistic plasma dispersion function. Special attention is given to the Weible and two-stream instabilities and to the normal modes of a quiescent, hot electron gas. For the last case the dispersion relations are solved numerically and compared against computer simulation data. An appendix applies the formalism to cold plasmas. 相似文献
5.
Summary The screening length of the deuterium ion by surrounding electrons in a palladium metal lattice, as estimated using two approaches—viz. the Thomas-Fermi screening theory and the Debye screening theory for plasmas in metal—is found to be less than the interatomic
separation of ordinary hydrogen molecules. This has important implications for the possibility of cold nuclear fusion at room
temperature, since slight fluctuations in equilibrium conditions may drive the deuterons to fuse together. The relative magnitudes
of screening length for the cold nuclear fusion regime and classical hot nuclear regimes (inertial and magnetic confinement)
reveal that in the former a comparatively smaller amount of energy is needed to overcome the repulsive Coulomb barrier between
two deuterium ions. 相似文献
6.
BISWAJIT SAHU 《Pramana》2011,76(6):933-944
Small amplitude quantum ion-acoustic solitary waves are studied in an unmagnetized two- species relativistic quantum plasma
system, comprised of electrons and ions. The one-dimensional quantum hydrodynamic model (QHD) is used to obtain a deformed
Korteweg–de Vries (dKdV) equation by reductive perturbation method. A linear dispersion relation is also obtained taking into
account the relativistic effect. The properties of quantum ion-acoustic solitary waves, obtained from the deformed KdV equation,
are studied taking into account the quantum mechanical effects in the weak relativistic limit. It is found that relativistic
effects significantly modify the properties of quantum ion-acoustic waves. Also the effect of the quantum parameter H on the nature of solitary wave solutions is studied in some detail. 相似文献
7.
V. V. Antsiferov 《Technical Physics》1998,43(10):1165-1171
The main parameters of the plasma of high-current hydrogen-cesium glow discharges of surface-plasma (planotron and Penning)
sources of negative hydrogen ions are determined using contact-free spectroscopic methods and compared for identical discharge
current densities. The elemental and charge composition of the plasma is established. The temperature of the hydrogen atoms
and the energy of the visible-range radiation of the plasma discharge are measured and estimates of the electron density in
the plasma are made. The dynamics of the change in the parameters of the discharge plasma of a Penning source — the densities
of hydrogen atoms, cesium atoms and ions, and molybdenum atoms — is tracked during a discharge pulse with spatial resolution
along two coordinates. It is observed that cesium atoms and ions and molybdenum atoms are pent up near the cathode surface.
Zh. Tekh. Fiz. 68, 32–38 (October 1998) 相似文献
8.
Vishnu M Bannur 《Pramana》2001,57(4):755-761
We derive relativistic fluid set of equations for neutrinos and electrons from relativistic Vlasov equations with Fermi weak
interaction force. Using these fluid equations, we obtain a dispersion relation describing neutrino beam plasma instability,
which is little different from normal dispersion relation of streaming instability. It contains new, nonelectromagnetic, neutrino-plasma
(or electroweak) stable and unstable modes also. The growth of the instability is weak for the highly relativistic neutrino
flux, but becomes stronger for weakly relativistic neutrino flux in the case of parameters appropriate to the early universe
and supernova explosions. However, this mode is dominant only for the beam velocity greater than 0.25c and in the other limit electroweak unstable mode takes over. 相似文献
9.
Lars Samuelsson C. S. Lopez-Monsalvo N. Andersson G. L. Comer 《General Relativity and Gravitation》2010,42(2):413-433
We study the (local) propagation of plane waves in a relativistic, non- dissipative, two-fluid system, allowing for a relative
velocity in the “background” configuration. The main aim is to analyze relativistic two-stream instability. This instability
requires a relative flow—either across an interface or when two or more fluids interpenetrate—and can be triggered, for example,
when one-dimensional plane-waves appear to be left-moving with respect to one fluid, but right-moving with respect to another.
The dispersion relation of the two-fluid system is studied for different two-fluid equations of state: (i) the “free” (where
there is no direct coupling between the fluid densities), (ii) coupled, and (iii) entrained (where the fluid momenta are linear
combinations of the velocities) cases are considered in a frame-independent fashion (e.g.no restriction to the rest-frame
of either fluid). As a by-product of our analysis we determine the necessary conditions for a two-fluid system to be causal
and absolutely stable and establish a new constraint on the entrainment. 相似文献
10.
11.
N. N. Rozanov 《Optics and Spectroscopy》2004,97(2):280-281
An estimate of the ratio of the contributions of relativistic and nonrelativistic factors to the Kramers-Kronig relations for a medium with spatial dispersion is performed in a form taking into account the relativistic requirement of the finiteness of the velocity of propagation of a signal. Even under conditions of comparatively strong spatial dispersion, in the case of Wannier-Mott excitons in typical semiconductors, this ratio proves to be very small—of the order of 10?4, which justifies the conventional (nonrelativistic) form of the dispersion relations. 相似文献
12.
A slow wave structure named Π — line is analysed in this paper. This circuit propagates slow waves in symmetrical and antisymmetrical
mode. The dispersion relations of both symmetrical and antisymmetrical modes are derived here, by means of the field matching
method. Numerical results are also given in this paper. The Π — line slow wave structure is of large diameter, and its radial
supported stubs provide good heat conduction paths. These properties make this circuit well suited for use in high power,
millimeter wave traveling wave tubes. 相似文献
13.
A. Yu. Didyk 《Physics of Particles and Nuclei Letters》2012,9(2):186-191
Studies of the storage and redistribution of hydrogen atoms under pulse high temperature hydrogen plasma that was obtained
using a PF-4 Plasma Focus facility in a multilayered structure (sandwich) which consists of two high-purity niobium foils
and a deuterium polyethylene film pressed between them have been carried out using the method for elastic recoil detection
(ERD). It was established that, with an increase in pulses of the PF-4 facility, the redistribution of implanted hydrogen
atoms for large depths occurs in the two Nb foils and deuterated polyethylene. The depths substantially exceed the projective
range of paths of hydrogen ions (at their maximum velocity of ∼108 cm/s). A maximum hydrogen concentration of 45 at % is reached in the nearest surface of the second Nb foil to the PF-4 at
20 pulses of hydrogen plasma. An X-ray diffraction analysis showed the presence of a niobium hydride phase in both Nb foils.
The redistribution of deuterium atoms from the bound state of deuterated polyethylene into the near-surface layer and the
bulk material of the second Nb foil was detected as well. This phenomenon can be attributed to the transfer of implanted hydrogen
atoms through the foil assembly and the transfer of deuterium from deuterated polyethylene into the near-surface layer of
the second foil under the effect of powerful shock waves that are created by pulse hydrogen plasma and by acceleration in
the diffusion of hydrogen and deuterium in the strain field induced by the shock wave. 相似文献
14.
A. E. Krupina 《Radiophysics and Quantum Electronics》1972,15(4):389-391
The transverse propagation of plasma waves in a magnetically active plasma near the harmonics of the electron gyrofrequency is considered for the condition that the wavelength is shorter than the gyroradius of an electron. Besides relativistic effects [14], collisions of electrons with other particles are taken into account. The derived dispersion equation is analyzed in the particular cases of weak and strong collisions, and likewise as a function of the resonant frequency detuning.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 15, No. 4, pp. 517–520, April, 1972.The author thanks B. N. Gershman for his constant help with the work. 相似文献
15.
The dispersion relation of electromagnetic waves propagating perpendicular to an applied uniform magnetic field B0 in relativistic plasma is derived. Waves propagating perpendicular to the uniform applied magnetic field can be separated into two modes - one is the linearly polarized transverse wave and the other is a hybrid mode. In the present analysis, dispersion relation of the first mode i. e., for a pure transverse wave is analysed under the assumption that the wavelength is much longer than the cyclotron radii of the electrons. A stability criterion which limits the thermal energy of the electrons along B0 is obtained. 相似文献
16.
In the present paper the problem of nonlinear interaction of two mildly-relativistic circularly polarized lasers in a cold plasma is studied in order to investigate electromagneticaily induced transparency (EIT). Based on a relativistic kinetic model, by expansion of relativistic Lorentz factor in terms of lasers amplitude, we obtain the coupled nonlinear dispersion relations. It is observed that due to resonance in the second harmonic of plasma beat-wave, the new EIT pass-band is created in the high intensities of lasers. The effect of amplitude and frequency variation on the dispersion is numerically investigated. 相似文献
17.
Brandt H.E. Uhm H.S. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1988,16(2):264-269
The cubic approximation to the dispersion relation for a relativistic backward-wave oscillator is obtained, and the utility and limits of the approximation are presented. The approximation is obtained by Taylor series expansion of the wave admittance in the dispersion relation for the transverse-magnetic and free-streaming modes of a relativistic, thin, hollow, cylindrical electron beam moving along the axis of a disc-loaded waveguide in a strong axial magnetic field. The resulting cubic dispersion relation yields instability growth rates and frequencies which fall off beyond their maximum more sharply with increasing wavenumber than for the complete dispersion relation. The approximation is found to be quite good near the operating points of contemporary high-power relativistic backward-wave oscillators, namely, for relatively long wavelength and small ratio of Budker's parameter to the relativistic gamma factor of the beam 相似文献
18.
Collinear laser—fast alkaline-earth ion beam interaction can be monitored sensitively by a detection sequence consisting of
optical pumping to a metastable state, state-dependent neutralization, and separate counting of ions and atoms. Deceleration
of the ions prior to neutralization strongly increases the sensitivity of the method. For ions with hyperfine split transitions
the sensitivity can be considerably improved by a two-step optical pumping sequence. In this contribution, the results of
rate equation calculations are compared to experimental results for Ba-and Sr-beams, including a shortlived99Sr beam of very low intensity. 相似文献
19.
The physical and optical properties of plasmas are depended on dynamics of species in the discharge volume. Then, the presence of an electron beam, as a separate component, in a dusty plasma can modify the plasma structures through altering the discharge parameters. In this report, the linear propagation of acoustic modes in a collisionless dusty plasma contains electrons, ions and charged dust grains is investigated in the presence of an electron beam. Our analysis indicates that the electron beam can modify the dispersion relations of dust acoustic modes which resulted different data transportation in dusty plasmas. The obtained results are also examined for negative and positive charged dust grains with different number densities. The charge of dust grains represents an important role in the dynamics of the low frequency waves. Additionally, our findings reveal that the propagation of acoustic waves in dusty plasmas can be controlled by adjusting the electron number density of the beam and the cathode potential. Lastly, we obtian the destabilizing effects, originated from dust charge fluctuation, by reconsidering the dispersion relations of both dust acoustic modes. 相似文献
20.
Wave growth rate in a cylindrical metal waveguide with ion-channel guiding of a relativistic electron beam 下载免费PDF全文
This paper addresses the formulae and numerical issues related to the possibility that fast wave may be grown when a relativistic electron beam through an ion channel in a cylindrical metal waveguide.To derive the dispersion equations of the beam-wave interaction,it solves relativistic Lorentz equation and Maxwell’s equations for appropriate boundary conditions.It has been found in this waveguide structure that the TM 0m modes are the rational operating modes of coupling between the electromagnetic modes and the betatron modes.The interaction of the dispersion curves of the electromagnetic TM 0m modes and the upper betatron modes is studied.The growth rates of the wave are obtained,and the effects of the beam radius,the beam energy,the plasma frequency,and the beam plasma frequency on the wave growth rate are numerically calculated and discussed. 相似文献