Electromagnetic Field In Plasma Research Articles

PIC-DSMC simulation of nonequilibrium capacitively coupled plasma in low pressure

In recent years, the interaction of electrons with the electromagnetic field in plasma at low pressure has received significant attention because of its high application. In low-pressure plasma, electrons can move long distances without any collisions in physical dimensions of the problem. This causes nonlocal dynamics, which leads to strong time and space dependence on and anisotropy of the distribution function. In this paper, a hybrid Particle-in-Cell (PIC) method with Direct Monte Carlo Simulation (DSMC) was proposed to investigate electron interactions with the electrostatic field. A capacitively coupled plasma (CCP) reactor at low pressure (0.01–10Pa) was also investigated. The effect of electric field was studied on electrons and field distribution in the computational domain at different times. Also, the amplitude current was investigated in a complete radio frequency (RF) cycle. As a result, this work proposed tools to examine the discharge flow for accurate knowledge of CCP discharge for optimization of reactors and its related processes.

A single long electron bunch detect electromagnetic field evolution in laser plasma

Laser fusion research needs much more high-time-resolved diagnostic technologies to study the dynamic process in laser plasma. We develop a special method and setup a device to measure the electromagnetic field in the plasma by using a single electron bunch. The measurement covers the whole-time window of the plasma process driven by a 3.6 ns laser pulse. An electron source can generate a single electron bunch with 0–100 keV energy and 10ns bunch length. A laser pulse with 1 J energy and 532 nm wavelength irradiates on the edge of a silver target, the target nearby the irradiated spot is ionized into plasma. At the beginning of plasma generation, the head of the electron beam begins to pass through the plasma. Electromagnetic field in plasma pushes the electrons transversely. A high voltage pulse at a good time is used to deflect the electrons linearly in the transverse direction to avoid overlapping of the different electrons on the scintillator downstream. By analyzing the deflection distances of the different electrons in this single bunch, we succesfully achieve an average electronic field along the trajectory in the plasma in the whole plasma process. The maximum value of this electronic field is <inline-formula> <tex-math id="M2">\begin{document}$ 7.74\times {10}^{5}\;\mathrm{V}/\mathrm{m} $\end{document}</tex-math> <alternatives> <graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="1-20211374_M2.jpg"/> <graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="1-20211374_M2.png"/> </alternatives> </inline-formula>.

Longitudinal phase space manipulation with planar corrugated wakefield structures

Wakefield structures have found a broad range of applications in beam longitudinal phase space manipulation in recent years. In this paper, we report on several electron beam manipulation experiments with planar corrugated wakefield structures following a photocathode RF gun, in which the bunch length of the electron beams are much longer, comparable, and much shorter than the characteristic wavelength of the corrugated structures, respectively. (1) A 15.6-ps beam forms a 0.17-THz bunch train via ballistic bunching, after gaining periodic energy modulation through these structures via self-induced wakefield. (2) For a 6-ps beam, the combination of wake structures and a drift converts its flat-top longitudinal profile into a ramped shape, remarkably improving its capability of efficiently exciting electromagnetic fields in plasma. (3) A 0.2-pC, 250-fs electron pulse subject to a drive beam’s wake is manipulated for different purposes, such as acceleration or deceleration with a ±200 keV gain in energy; or compression to ∼70 fs via ballistic compression. The results illustrate the unique and versatile capability of wakefield structures in beam manipulation for various applications. The simplicity, robustness, and inherent synchronization of such devices may open up many new possibilities in accelerator facilities.

Excitation of Gould–Trivelpiece mode by streaming particles in dusty plasma

AbstractIn this paper, we study the excitation of Gould–Trivelpiece (TG) waves by streaming ions in dusty plasma and derive the dispersion relation of the excited waves using first-order perturbation theory. The motion of charged particles is controlled by electromagnetic fields in plasma. The energy transfer processes which occur in this collisionless plasma are believed to be based on wave–particle interactions. We have found that the TG waves may be generated in a streaming ion plasma via Cerenkov interaction, and the ions may be accelerated by TG waves via cyclotron interaction, which enable energy and momentum transfer. The variation in the growth rate of TG wave with dust grain size and relative density of negatively charged dust grains is also studied. The dust can cause an unstable TG mode to be stable in Doppler resonance, and can induce an instability in Cerenkov interaction.

Generation of the relic neutrino asymmetry in a hot plasma of the early universe

The neutrino asymmetry in the early universe plasma, [Formula: see text], is calculated both before and after the electroweak phase transition (EWPT). In the Standard Model, before EWPT, the leptogenesis is well known to be driven by the abelian anomaly in a massless hypercharge field. The generation of the neutrino asymmetry in the Higgs phase after EWPT, in its turn, has not been considered previously because of the absence of any quantum anomaly in an external electromagnetic field for such electroneutral particles as neutrino, unlike the Adler–Bell–Jackiw anomaly for charged left and right polarized massless electrons in the same electromagnetic field. Using the neutrino Boltzmann equation, modified by the Berry curvature term in the momentum space, we establish the violation of the macroscopic neutrino current in plasma after EWPT and exactly reproduce the nonconservation of the lepton current in the symmetric phase before EWPT arising in quantum field theory due to the nonzero lepton hypercharge and corresponding triangle anomaly in an external hypercharge field. In the last case, the nonconservation of the lepton current is derived through the kinetic approach without a computation of corresponding Feynman diagrams. Then, the new kinetic equation is applied for the calculation of the neutrino asymmetry accounting for the Berry curvature and the electroweak interaction with background fermions in the Higgs phase. Such an interaction generates a neutrino asymmetry through the electroweak coupling of neutrino currents with electromagnetic fields in plasma, which is [Formula: see text]. It turns out that this effect is especially efficient for maximally helical magnetic fields.

Self-localized and self-constricted electromagnetic field in plasma and atmosphere

A possibility of creation of a super-high-frequency electromagnetic-field clot in the plasma is shown. Two cases of the field self-localization in the plasma are considered. In the first case, a super-high-frequency electric field creates an annular channel by displacing the plasma and induces a curl-like magnetic field inside. In the second case, the electric field creates a toroidal channel where different field structures are possible. For example, the magnetic lines of the force are aligned along the big circle of the torus, while the curl-like electric lines are aligned along the small circle. Otherwise, the magnetic field is curl-like and the electric-field lines are aligned along the big circle. We evaluate the electric field energy that is required for a curl-like structure of about 3 cm in size to exist during 10 s in the atmospheric air. This energy sustains plasma in the vicinity of the curl-like area.

Determination of the energy of a relativistic electron beam by measuring the thickness of the colored layer in glass

A method for determining the energy of relativistic electrons, which was used in the investigation of electromagnetic fields in plasma and dielectric structures, is described. The electron energy was determined by the extrapolated track of electrons in glass, which was estimated by the thickness of the colored (darkened) layer formed by electrons. The density distribution of the colored layer along the direction of electron motion makes it possible to record the width of the beam energy spectrum and the beam position relative to the axis of the transit channel. A stack of glass plates on which the beam is incident can be installed in the transit channel of the dielectric structure or in plasma. Each plate in the stack is placed in parallel to the beam axis. After irradiation of the plates with relativistic electrons, the colored layer depth and the density distribution are determined. Examples of determining the electron energy of a pulsed relativistic electron beam are presented. The method is insensitive to electromagnetic noise, is inexpensive, simple, and easy to use.

Plasma-Induced Degradation of Polypropene Plastics in Natural Volatile Constituents of Ledum palustre Herb

Polypropene (PP) plastics can be effectively degraded by natural volatile constituents from Ledum palustre catalyzed by atmospheric air dielectric barrier (DBD) plasma. The electron spin resonance (ESR) result indicates that the volatile constituents produce radicals in aerobic condition energized by power sources such as light, UV, plasma and so on. The degradation is a novel chemically oxidative way and it is initiated by a series of radical reactions. Lots of active and oxidative species, radicals, products and high energy electromagnetic field in plasma aggravate the degradation process. The results about PP maximum tensile strength (σbmax) confirm this conclusion. PP plastic heavily loses its extensibility, mechanical integrity and strength in a short time after suffering a synergetic treatment of the herb extract and air DBD plasma with no toxic residues left. The components of herb extract keep almost unchanged and may be reused. This study offers a new approach to manage and recycle typical plastics.

Modulation instability of intense laser beam in an electron–positron plasma

Modulation instability of an intense right-hand elliptically polarized laser beam propagating through an electron–positron plasma is investigated by a new method. The nonlinear dispersion relation, in which the relativistic and ponderomotive nonlinearities are taken into account, is obtained for the laser radiation in electron–positron plasma by the Lorentz transformation. The Karpman equation is generalized to the case of three dimensions with three field components. When the nonlinear frequency shift of the electromagnetic field in plasma is involved, the nonlinear evolution equation for the slowly varying envelope of the laser field is obtained. Thus, modulation instability of the intense laser beam in electron–positron plasma is studied and the temporal growth rate of the instability is derived. The analysis shows that the growth rate of modulation instability is increased significantly near the critical surface in a laser-plasma.

Self-modulation instability of an intense laser beam in a magnetized pair plasma

The modulation instability of an intense right-hand elliptically polarized laser beam propagating through a magnetized pair plasma is investigated. The nonlinear dispersion relation, in which the relativistic and ponderomotive nonlinearities are taken into account, is obtained for the laser radiation in a magnetized pair plasma by Lorentz transformation. When the nonlinear frequency shift of the electromagnetic field in plasma is involved, the nonlinear evolution equation for the slowly varying envelope of the laser field is obtained. Thus, the modulation instability of the intense laser beam in a magnetized pair plasma is studied and the temporal growth rate of the instability is derived. The analysis shows that the peak growth rate of self-modulation instability is increased due to the axial magnetization of plasma.

Modulation instability by intense laser beam in magnetized plasma

Modulation instability of an intense right-hand elliptically polarized laser beam propagating through magnetized plasma is investigated by a new method. The nonlinear dispersion relation, in which the relativistic and ponderomotive nonlinearities are taken into account, is obtained for the laser radiation in magnetized plasma by the Lorentz transformation. The Karpman equation is firstly generalized to the case of three dimensions with three field components. When the nonlinear frequency shift of the electromagnetic field in plasma is involved, the nonlinear evolution equation for the slowly varying envelope of the laser field is obtained. Thus, modulation instability of the intense laser beam in magnetized plasma is studied and the temporal growth rate of the instability is derived. The analysis shows that the peak growth rate of self-modulation instability is increased due to the axial magnetization of plasma. It is also shown that the growth rate of modulation instability is increased significantly near the critical surface in a laser–plasma.

Ion acceleration by multiple laser pulses and their spontaneous electromagnetic fields in plasma

AbstractThe acceleration of ions by multiple laser pulses and their spontaneously generated electric and magnetic fields is investigated by using an analytical model for the latter. The relativistic equations of motion of test charged particles are solved numerically. It is found that the self-generated axial electric field plays an important role in the acceleration, and the energy of heavy test ions can reach several gigaelectronvolts.

Analytical description of rippling effect and ion acceleration in plasma produced by a short laser pulse

In this paper we present the analytical description of two processes dealing with the skin-layer ponderomotive acceleration method of fast ion generation by a short laser pulse: ion density rippling in the underdense plasma region and generation of ion beams by trapped electromagnetic field in plasma. Some numerical examples of hydrodynamic simulation illustrating these processes are shown. The effect of using the laser pulse consisting of different frequency components on the ion density rippling and on phenomena connected with trapped electromagnetic field is analyzed.

Characterization of the slot antenna microwave plasma source

An annular ring slot antenna is used as the generation of large-volume 2.45-GHz microwave plasma. With argon, a surface wave at the quartz tube can be excited above 250 W. Optical emissions testify the existence of azimuthal modes of m=4 at a pressure of 10 Pa and m=6 at a pressure of 230 Pa. An important conclusion that the uniformity of electromagnetic field in plasma has a dependence on the value of plasma density has been acquired based on theoretical calculations under low pressures. Meanwhile, the efficiency of the plasma source is investigated experimentally. Especially, the spatial distribution of plasma parameter show that homogeneous plasma cylinder with a diameter of 160 mm has been successfully produced at the pressure of 10-1000 Pa.

On the Theory of Parametric Excitation of Electron Plasma

The possibility of parametric excitation of longitudinal and transverse oscillations of pure cold electron plasma in high-frequency electric fields, when the relativistic oscillatory motion of the plasma electrons is taken into account, is studied. It is shown that the longitudinal and transverse oscillations are parametrically excited. Two equations describing the growth-rate of longitudinal and transverse oscillations and the parametric resonance conditions are obtained. It is also shown that due to the decrease of the proper plasma frequency, the penetration depth of electromagnetic fields in plasma is increased.

Certain relativistic effects due to strong electromagnetic fields in plasma

It is shown that the propagation of a strong electromagnetic wave in an electron plasma can lead to a generation of a constant electron current along the direction of propagation and to a large increase in the average electron density.

High frequency electromagnetic field in plasma with negative dielectric constant

A nonlinear mechanism is considered for the penetration of a transverse electromagnetic field into plasma with E=1- omega 02<0 and Te>>Ti. It is shown that the modulated finite amplitude electromagnetic wave produces plasma density fluctuations which form an electro-acoustic wave and transmits the electromagnetic field into the plasma with a velocity of the order of that ion sound. A theory describing the formation and evolution of the electroacoustic waves is developed.