Maser based on cyclotron resonance in a decaying plasma

The features of generating electromagnetic radiation in a two-level cyclotron maser whose active medium is a decaying nonequilibrium plasma confined in a magnetic field with the mirror configuration have been examined. It has been shown that, even in the absence of a continuously acting source of nonequilibrium particles (inversion of the medium), the system can exhibit the regimes of the quasimonochromatic or pulse generation of radiation owing to a fast monotonic decrease in the instability threshold that is characteristic of the plasma decay. The theory is confirmed by the results of observations of the burst activity of the decaying pulsed-discharge plasma under the conditions of the electron cyclotron resonance in the direct axisymmetric magnetic trap.     

High-voltage pulsed discharge in an electron source with a plasma cathode

The nature of and mechanism for producing a high-voltage discharge in an electron source with a plasma cathode are investigated. The possibility of generating pulsed electron currents with an amplitude of 10³–10⁴ A and a length of 10^–6 sec is considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 117–121, October, 1973.The authors thank B. M. Koval'chuk for help in developing the experimental arrangement and G. A. Mesyates for constant attention to the work and discussion of the results.     

Transients and efficient generation of electron beams in the pulsed wide-aperture glow discharge

The quasi-continuous wide-aperture glow discharge in helium at pressures from 1.2 to 6.0 Torr is studied. It is found that electron beam generation efficiency η is higher than 96% in the pressure range 1.2–3.0 Torr at voltages from 1.0 to 2.6 kV. The maximum power was ≈ 0 kW at 6 Torr and a voltage across the discharge gap of 2.6 kV. Under these conditions, the beam generation efficiency is about 80%. The pressure and voltage dependences of main parameters of the discharge are explained from the standpoint of its photoemission nature.     

Track measurements of fast particle streams in pulsed discharge explosive plasma

This paper reports results of track registration for fast particles from the hot spot sparked inside a metal target. CR-39 track detectors placed in the ion pinhole camera, a magnetic analyzer, and Thomson-type mass-spectrometer in order were used to obtain images of the hot spot and to determine spectra of the fast particles. Using track detectors in the pinhole camera, we have obtained specific split images. The “average etch rate ratio versus track length” locus for track sample groups is depicted by means of squared diameters asymptotic method. Our analysis shows the majority of tracks belong to hydrogen nuclei. The track loci for the detectors from the pinhole or analyzers turn out to be split into two parallel streaks that have been interpreted as a proton–deuteron doublet. Data obtained using the Thomson analyzer clearly demonstrate the equal numbers of protons and deuterons for some parallel parabola sections.     

Electron boltzmann kinetic equation averaged over fast electron bouncing and pitch-angle scattering for fast modeling of electron cyclotron resonance discharge

The electron distribution function (EDF) in an electron cyclotron resonance (ECR) discharge is far from Maxwellian. The self-consistent simulation of ECR discharges requires a calculation of the EDF on every magnetic line for various ion density profiles. The straightforward self-consistent simulation of ECR discharges using the Monte Carlo technique for the EDF calculation is very computer time expensive, since the electron and ion time scales are very different. An electron Boltzmann kinetic equation averaged over the fast electron bouncing and pitch-angle scattering was derived in order to develop an effective and operative tool for the fast modeling (FM) of low-pressure ECR discharges. An analytical solution for the EDF in a loss cone was derived. To check the validity of the FM, one-dimensional (in coordinate) and two-dimensional (in velocity) Monte Carlo simulation codes were developed. The validity of the fast modeling method is proved by comparison with the Monte Carlo simulations. The complete system of equations for FM is presented and ready for use in a comprehensive study of ECR discharges. The variations of plasma density and of wall and sheath potentials are analyzed by solving a self-consistent set of equations for the EDF.     

Particle loss from an electron cyclotron resonance discharge plasma in the WT-2 device

The dominant particle loss from an electron cyclotron resonance discharge plasma in a simple toroidal configuration is ascribed to the $\text{E}\text{×}\text{B}$ drift due to the vertical electric field produced by the electrons' toroidal drift. The electron density is increased by adding a small vertical field. This is explained by the electron flow along the line of force canceling the toroidal drift, resulting in reduction of the $\text{E}\text{×}\text{B}$ drift.     

Observation of second harmonic generation by surface waves in a gas discharge plasma

The propagation of a second harmonic surface wave in a gas discharge plasma is investigated experimentally. The results are compared with those obtained for surface waves excited directly.     

A reflex electron beam discharge as a plasma source for electronbeam generation

A reflex electron beam glow discharge has been used as a plasma source for the generation of broad-area electron beams. An electron current of 120 A (12 A/cm²) was extracted from the plasma in 10 μs pulses and accelerated to energies greater than 1 keV in the gap between two grids. The scaling of the scheme for the generation of multikiloamp high-energy electron beams is discussed     

栅网与偏压对CHF3电子回旋共振放电等离子体特性的影响

研究了电子回旋共振等离子体增强化学气相沉积系统中栅网的增加和栅网上施加+60V和-60V偏压对CHF3放电等离子体特性的影响.发现在低微波功率下栅网与偏压对等离子体中基团分布的影响较大,而高微波功率下的影响逐渐减小.这是由于低微波功率下等离子体中电子温度较低,基团的分布同时受栅网鞘电场和电子碰撞分解的共同作用;而高微波功率下电子温度较高,栅网鞘电场的作用减弱,基团分布主要取决于电子碰撞分解作用.     

电子回旋共振离子推力器放电室等离子体数值模拟

电子回旋共振离子推力器属于静电型推力器,具有寿命长、比冲高、结构简单、可靠性高等优点,适用于深空探测等长时间空间飞行任务.放电室是一个关键部件,其内部通过电子回旋共振产生等离子体.针对放电室内等离子体流场建立飘移-扩散近似模型,采用迎风格式有限差分法对该模型进行数值求解,得到了放电室内不同时刻的等离子体流场分布及其演化规律.数值模拟结果可以为推力器的设计和实验研究提供有用信息.     

Formation of CNx thin films by reactive pulsed laser deposition assisted by electron cyclotron resonance microwave discharge

Amorphous carbon nitride thin films were synthesized by pulsed laser deposition combined with electron cyclotron resonance (ECR) microwave discharge in nitrogen gas. The ECR discharge supplies active nitrogen species in the deposition environment and to the growing film surface, enhancing the film growth in complex processes accompanied by chemical reaction. The synthesized films were characterized by Rutherford backscattering spectroscopy (RBS), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. The films were determined to consist purely of carbon and nitrogen with a nitrogen concentration of 42%, and have a thickness of 550 nm over which carbon and nitrogen are well distributed. Structural characterizations based on XPS, FTIR and Raman analysis showed that these films appear to contain several bonding configurations between carbon and nitrogen with a small amount of C≡N bonds compared with other bonding states. Received: 31 August 2000 / Accepted: 12 December 2000 / Published online: 23 May 2001     

Parametric generation of low-frequency waves by plasma electrons accelerated under electron cyclotron resonance conditions

It has been shown experimentally that the diamagnetic effect appearing when electrons of a magnetized plasma in the antenna near field are accelerated under electron cyclotron resonance conditions can be used to generate low-frequency waves. The amplitude modulation of a signal supplied to the antenna is accompanied by the modulation of the diamagnetic effect and leads to the emission of waves at the modulation frequency to the surrounding plasma. In this process, the extended plasma region containing accelerated electrons serves as a parametric bodiless antenna. The results of the model laboratory experiments make it possible to propose a method for the parametric generation of low-frequency whistler waves in the Earth’s ionosphere by a powerful amplitude-modulated signal supplied to the satellite-borne antenna.     

Microwave preionization of the tokamak discharge at the electron cyclotron resonance

When ohmic heating power is applied during the microwave discharge at the electron cyclotron resonance, the plasma current and density build-up become fast and the loop voltage required to start the tokamak discharge decreases. The micro-wave burst observed in the initial stage is reduced and the burst of hard X-rays, occurring at the quasi-steady stage of discharge in the case of no microwave injection, disappears, suggesting that the production of run-away electrons is suppressed strongly.     

Quasi-linear relativistic treatment of electron cyclotron fluctuations in a magnetized plasma

Summary The relativistic quasi-linear theory of electron cyclotron fluctuations is developed for a homogeneous plasma. Expressions are given for the absorption and emission coefficients, consistently with the currently employed linear theory. The extension to the inhomogeneousplasma case is considered and shown to allow the analysis of wave propagation, absorption and emission in plasmas of physical interest.

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Riassunto Si sviluppa la teoria quasi lineare relativistica per le fluttuazioni di onde elettroniche di ciclotrone per un plasma omogeneo. Si otteggono inoltre le espressioni dei coefficienti d'assorbimento ed emissione del plasma, consistentemente con la teoria lineare correntemente usata. Si considera infine l'estensione della teoria ad un plasma disomogeneo, applicandola all'analisi quantitativa di propagazione, assorbimento ed emissione di onde di ciclotrone.

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Резюме Для однородной плазмы развивается релятивистская квазилинейная теория электронных циклотронных флуктуаций. Приводятся вйражения для коэффициентов поглощения и испускания, соответствующих повсеместно используемой линейной теории. Рассматривается обобщения и излучения волн в плазме в физическн интересных случаях.

     

Fast electron generation in a laser plasma

Fast electron generation via Langmuir turbulence is discussed. It is shown that the distribution of fast electrons is maxwellian. The connection between the hot temperature and the turbulence parameters is found.     

Excitation of electron cyclotron harmonic waves due to helical electron beams in a plasma

Instabilities of electron cyclotron harmonic waves due to the anisotropy of the velocity distribution of electrons which was produced by the injection of the electron beam perpendicular to the magnetic field have been observed.     

Estimates of the electron density in an ECR source of calcium plasma

A technique is proposed for estimating parameters of the plasma produced by a source based on the electron cyclotron resonance. The analysis is made for the ion cyclotron resonance (ICR) facility designed for separating calcium isotopes. It is assumed that the resonance condition for an extraordinary wave is fulfilled for electrons moving towards the wave. The plasma optical thickness, the transverse energy of resonance electrons, and its dependence on the longitudinal velocity are determined. The charged particle density in the plasma flow is estimated in terms of the balance of the electrons generated as a result of vapor ionization in the discharge zone and the electron losses due to longitudinal ambipolar diffusion.     

Quasi-optical simulation of the electron cyclotron plasma heating in a mirror magnetic trap

The resonance microwave plasma heating in a large-scale open magnetic trap is simulated taking into account all the basic wave effects during the propagation of short-wavelength wave beams (diffraction, dispersion, and aberration) within the framework of the consistent quasi-optical approximation of Maxwell’s equations. The quasi-optical method is generalized to the case of inhomogeneous media with absorption dispersion, a new form of the quasi-optical equation is obtained, the efficient method for numerical integration is found, and simulation results are verified on the GDT facility (Novosibirsk).