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The role of electric field on the different power coupling processes is reported during evolution of over-dense plasma inside a microwave (MW) discharge ion source (MDIS). This power coupling through different parametrically induced waves can yield very high density plasma and self-focused ion beam. Unlike PIC/MCC or hybrid fluid, here the FEM based fluid model uses time dependent Poisson solver through drift-diffusion approach. Results demonstrate that the pumping wave (2.45GHz) energy decays through electron cyclotron resonance (ECR), scattered upper hybrid (UH)/electron Bernstein wave (EBW), polarization reversal and ion type waves(i.e., Ion Bernstein wave (IBW),Ion Acoustic Wave (IAW), Electrostatic Ion cyclotron wave(EICW)) respectively with the advancement of time of MW launching. ECR based power absorption takes place up to 5 $\mu \mathrm{s}$ , till it reaches the critical density. The energy channeling through different waves is determined by the plasma density gradient, the pump wave $\tilde{E}$ -field strength and its distribution within the cavity. The MW power absorption through UH/EBW starts occurring mainly from time t = ~ $40 \mu \mathrm{s}$ onwards since the initiation of plasma breakdown time. The change in guided-wave mode (m = +1 to -1, polarization reversal) frequency from low to high, comes into play from time $\mathrm{t}=\sim 25\mu \mathrm{s}$ at the polarization reversal point which is affected by E- field, magnetic field gradient, and the radial boundary condition. The theoretically obtained $\tilde{\mathrm{E}}$ -field was compared with the experimentally obtained EICWs intensity lines.

An ordinary mode electromagnetic wave can decay into an ion acoustic wave and a scattered electromagnetic wave by a process called stimulated Brillouin scatter (SBS). The first detection of this process during ionospheric modification with high power radio waves was reported by Norin et al. (2009) using the HAARP transmitter in Alaska. Subsequent experiments have provided additional verification of this process and quantitative interpretation of the scattered wave frequency offsets to yield measurements of the electron temperatures in the heated ionosphere. Using the SBS technique, electron temperatures between 3000 and 4000 K were measured over the HAARP facility. The matching conditions for decay of the high frequency pump wave show that in addition to the production of an ion-acoustic wave, an electrostatic ion cyclotron wave may also be produced by the generalized SBS processes. Based on the matching condition theory, the first profiles of the scattered wave amplitude are produced using the stimulated Brillouin scatter (SBS) matching conditions. These profiles are consistent with maximum ionospheric interactions at the upper-hybrid resonance height and at a region just below the plasma resonance altitude where the pump wave electric fields reach their maximum values.

We have studied the stability of the electrostatic ion cyclotron wave in a plasma consisting of isotropic hydrogen ions (H+) and temperature-anisotropic positively (O+) and negatively (O−) charged oxygen ions, with the electrons drifting parallel to the magnetic field. Analytical expressions have been derived for the frequency and growth/damping rate of ion cyclotron waves around the first harmonic of both hydrogen and oxygen ion gyrofrequencies. We find that the frequencies and growth/damping rates are dependent on the densities and temperatures of all species of ions. A detailed numerical study, for parameters relevant to comet Halley, shows that the growth rate is dependent on the magnitude of the frequency. The ion cyclotron waves are driven by the electron drift parallel to the magnetic field; the temperature anisotropy of the oxygen ions only slightly enhance the growth rates for small values of temperature anisotropies. A simple explanation, in terms of wave exponentiation times, is offered for the absence of electrostatic ion cyclotron waves in the multi-ion plasma of comet Halley.

Dispersion relation, resonant energy transferred, growth rate and marginal instability criteria for the electrostatic ion-cyclotron wave with general loss-cone distribution in low- β anisotropic, homogeneous plasma in the auroral acceleration region are discussed by investigating the trajectories of the charged particles. Effects of the parallel electric field, ion beam velocity, steepness of the loss-cone distribution and temperature anisotropy on resonant energy transferred and growth rate of the instability are discussed. It is found that the effect of the parallel electric field is to stabilize the wave and enhance the transverse acceleration of ions whereas the effect of steepness of loss-cone, ion beam velocity and the temperature anisotropy is to enhance the growth rate and decrease the transverse acceleration of ions. The steepness of the loss-cone also introduces a peak in the growth rate which shifts towards the lower side of the perpendicular wave number with the increasing steepness of the loss-cone.

The linearized dispersion relation describing waves in a plasma having a uniform magnetic field, uniform density, inhomogeneous parallel (to the magnetic field) flow, and thermal anisotropy (Ti⊥/Ti∥) is used to determine the threshold condition for growth of an electrostatic ion cyclotron wave and its harmonics. The inclusion of moderate ion thermal anisotropy (Ti⊥/Ti∥∼3) and parallel-flow shear (dVd/dx∼0.05Ωci), values typical of many space and laboratory plasmas, reduces the critical current necessary for instability growth to nearly zero. That an electrostatic instability conventionally associated with strong field aligned currents can be excited in the absence of any field aligned current and only by moderate parallel-flow shear suggests that ion cyclotron instabilities may play a larger role in many plasma environments than previously believed. The decrease in the instability threshold for increasing thermal anisotropy suggests that ion heating due to ion cyclotron waves may result in a positive feed...

Because of the implications for plasmas in the laboratory and in space, attention has been drawn to inhomogeneous energy-density driven (IEDD) waves that are sustained by velocity-shear-induced inhomogeneity in cross-field plasma flow. These waves have a frequency vr in the lab frame within an order of magnitude of the ion gyrofrequency vci, propagate nearly perpendicular to the magnetic field (kz /k^ << 1), and can be Landau resonant (0 < v1/kz < nd) with a parallel drifting electron population (drift speed nd), where subscripts 1 and r indicate frequency in the frame of flowing ions and in the lab frame, respectively, and kz is the parallel component of the wavevector. A transition in phase velocity from 0 < v1/kz < nd to 0 > v1/kz > nd for a pair of IEDD eigenmodes is observed as the degree of in-homogeneity in the transverse E × B flow is increased in a magnetized plasma column. For weaker velocity shear, both eigenmodes are dissipative, i.e. in Landau resonance, with kz nd > 0. For stronger shear, both eigenmodes become reactive, with one's wavevector component kz remaining parallel, but with v1/kz > nd , and the other's wavevector component kz becoming anti-parallel, so that 0 > v1/kz . For both eigenmodes, the transition (1) involves a small frequency shift and (2) does not involve a sign change in the wave energy density, which is proportional to vr v1, both of which are previously unrecognized aspects of inhomogeneous energy-density driven waves.

The instability of electrostatic ion cyclotron wave in a plasma consisting of isotropic hydrogen ions (H+), oxygen ions (both positively and negatively charged and denoted by O+ and O−) and electron. ESIC waves with multi component plasma have been studied by kinetic approach at different plasma densities. The dispersion relation and growth rate of the electrostatic ion-cyclotron waves with multi-ion plasma has been investigated. The effect of different plasma densities on ESIC waves in multi-ions is to enhance the growth rate of ESIC waves. The results are interpreted for the space plasma parameters appropriate to the auroral acceleration region of earth's magneto-plasma.

We have analysed the effect of non-thermal electrons on the interaction between the electrostatic ion-cyclotron wave and drift wave, taking into account the low frequency ponderomotive force. It is observed that one of the equation is a generalisation of the famous Hasegawa-Mima form with a non-zero right hand side representing interaction with ion cyclotron wave. In the second part we have treated only the drift wave equation in the non-interacting limit and have obtained exact vortex like solutions. Lastly, the modulational instability of the drift wave is studied in the non-interaction limit, by deriving a non-linear Schrodinger equation.

Electrostatic ion cyclotron wave fields are determined in a magnetized and weakly collisional plasma. A phased‐locked Laser Induced Fluorescence (LIF) diagnostic is used to directly measure the wave perturbed ion velocity distribution. Comparing these local LIF measurements with a theoretical model uniquely determines the wave parameters, such as the wave potential, the three‐dimensional wave vector, and the effective wave damping. The self‐consistent wave–particle interaction is modeled by Boltzmann–Poisson equations in the limit of weak collisions. The wave parameters determined from local measurements agree with those determined from spatial scans.

Summary form only given. Mesoscale models for the plasmasphere refilling reveal that the expansion of the ionospheric plasma into empty flux tubes during the early stage refilling produces highly supersonic counterstreaming ion beams. Such beams are found to meet the conditions for the instability of the electrostatic ion cyclotron (eic) waves in the equatorial plasmasphere. Since the spatial scale of the eic wave instability is determined by the ion Larmor radius and the corresponding time scale by the ion cyclotron period, it is unresolvable by the crude spatial and temporal resolutions afforded by the mesoscale models. Thus the eic waves and the associated microprocesses are missed out by the existing mesoscale refiling models based on the fluid and semikinetic approaches. We propose here an algorithm for incorporating the effects of eic waves on mesoscale plasma flow; the algorithm is based on the critical conditions for the eic instability. When the relative drift of the counterstreaming ion beams exceeds a critical value, depending on the beam temperatures, the excess momentum and energy are dissipated into thermal motion of the ions, resulting in ion heating in the degree of freedom perpendicular to the ambient magnetic field at the expense of the parallel ion drift. This leads to the creation of two distinct ion populations consisting of field-aligned counterstreaming ions and perpendicularly heated warm anisotropic ions trapped in the flux tube. The latter ions are created during the first few hours of the refilling process primarily in the equatorial region, but eventually they spread out all over the flux tube. Highly anisotropic ions are seen near the equator by the virtue of being locally created and trapped there. Estimates of the Coulomb collision time show that the warm anisotropic population (WAP) has a life time ranging from about 10 hours in the topside ionosphere to several days in the equatorial region. Thus, once initially created during early stage refilling, WAP ions become a common feature of the outer plasmasphere. The coexisting multiple ion populations, consisting of anisotropic warm ions and the field-aligned counterstreaming flows, have been observed from DE 1 on flux tubes undergoing refilling.

Theoretical considerations and high spatial resolution numerical simulations of radio frequency (rf) wave heating in tokamaks and in spherical toruses (ST) indicate that fast waves launched into tokamaks in the ion cyclotron range of frequencies (ICRF) or into spherical toruses in the high harmonic fast wave (HHFW) regime may excite a short wavelength slow mode inside of the plasma discharge due to the presence of hot electrons that satisfy the condition ω

Electrostatic plasma waves are excited in a laboratory plasma by means of the ponderomotive force of a high‐power, power‐modulated transversely excited atmosphere (TEA) CO2 laser beam [W. W. Duley, CO2 Lasers (Academic, New York, 1976), Chap. 2.5]. The strengths of the magnetic field, for which the plasma waves are excited selectively, and the group velocity of the excited plasma waves are consistent with the dispersion relation of the electrostatic ion cyclotron wave. This wave‐excitation experiment gives proof to the principles of the driven scattering plasma diagnostics which has been proposed as a method for the ion temperature measurement of high‐temperature plasmas.

The influence of transverse, localized, DC electric fields (TLEs) on the current-driven electrostatic ion-cyclotron (CDEIC) instability is being investigated in a Q machine. A small (diameter approximately 10 ion gyroradii) segmented disk electrode is being used to excite the mode in a narrow electron-current channel along which exists a radial electric field between regions that magnetically map to the different circular segments (separated by a radial gap of approximately 3 ion gyroradii). Experiments aimed at demonstrating a TLE dependence in the threshold current for mode excitation are described. A comparison of observed and predicted mode frequencies over a range of magnetic field strengths is presented for the benchmark case of no applied transverse electric field. When the electric field is present, ion-cyclotron fluctuations are observed for cases in which the current is below the CDEIC instability threshold. >

Heating experiments in the second harmonic ion cyclotron range of frequencies (ICRF) have been performed with a phased array of 2×2 loop antennas in JT-60. Properties of antenna-plasma coupling are examined by phasing antenna currents in the toroidal direction. In particular, it is first found that the antenna-plasma coupling resistance increases after the H-mode transition in out-of-phase excitation of antenna currents. This result is well explained with the cold plasma coupling theory which takes into account a change in the edge density profile at the transition. Two types of parametric decay instabilities near the plasma edge are observed. One type is decay into an ion Bernstein wave (IBW) and an ion cyclotron quasimode (IQM) and the other into an ion Bernstein wave and a cold electrostatic ion cyclotron wave (CESICW) or an electron quasimode (EQM). Intensity of IBW detected by a probe near the antenna in the decay into IBW and IQM increases with reduction of B T and I p . The decay instabilities are observed only in the case of in-phase excitation. The edge plasma is heated by the decay instability and the radiation loss during ICRF heating increases with the decay activity.

Electron attachment to perfluoromethylcyclohexane (C7F14) and sulfur hexafluoride (SF6) is studied in a Q machine which produces a thermally ionized potassium plasma at an electron temperature Te approximately = 0.2 eV (2300 K) . Negative ion formation is observed by Langmuir probe measurements of the reduction in electron density as electrons attach to C7F14 to form C7F14- or to SF6 to produce SF6- . In C7F14 at a pressure approximately 3x10(-5) Torr , a nearly electron-free plasma is formed with a residual electron-to-ion density ratio ne/n+ < 10(-4) . Formation of the C7F14- negative ion was confirmed by the presence of the C7F14- electrostatic ion cyclotron wave mode in the power spectrum of current-driven plasma oscillations. Measurements of the negative ion-to-electron density ratio, n_/ne for different pressures in both C7F14 and SF6 indicate that for thermal electrons at 2300 K larger values of n_/ne are obtained in C7F14 at a lower pressure than in SF6 .

A dynamics of a solitary pulse of the electrostatic ion cyclotron wave that propagates perpendicular to an applied magnetic field is considered. It is shown that the solitary wave will be singular in some range of parameters in the system, such as the plasma density and the magnitude of an applied magnetic field. This fact shows that there is a possibility of controlling the place where explosion of the solitary wave occurs.

A folded waveguide with E|| polarization is being installed on LHD device. The main purpose of the folded waveguide is to pre-ionize and create good target plasmas. The present manuscript proposes a launching of IBW via CESICW (Cold Electrostatic Ion Cyclotron Wave) for heating the core of LHD with the folded waveguide. The core heating can be accomplished by adding a minority hydrogen ion species in a helium majority plasma facilitating the mode-transformation of CESICW into IBW at the ion-ion hybrid resonance.

Nonlinear electron acoustic cyclotron waves (EACW) are studied in a quasineutral plasma in presence of uniform magnetic field. The fluid model is used to describe the dynamics of two temperature electron species in a stationary charge neutral inhomogeneous background. In long wavelength limit, it is shown that the linear electron acoustic wave is modified by the uniform magnetic field similar to that of electrostatic ion cyclotron wave. Nonlinear equations for these waves are solved by using Lagrangian variables. Results show that the spatial solitary wave-like structures are formed due to nonlinearities and dispersions. These structures transiently grow to larger amplitude unless dispersive effect is actively operative and able to arrest this growth. We have found that the wave dispersion originated from the equilibrium inhomogeneity through collective effect and is responsible for spatiotemporal structures. Weak dispersion is not able to stop the wave collapse and singular structures of EACW are formed. Relevance of the results in the context of laboratory and space plasmas is discussed.

Electrostatic waves in the ion cyclotron range of frequencies (ICRF) were studied in the Princeton L-4 and ACT-1 devices for approximately ten years, from 1975 to 1985. The investigation began in the L-4 linear device, looking for the parametric excitation of electrostatic ion cyclotron waves in multi-ion-species plasmas. In addition, this investigation verified multi-ion-species effects on the electrostatic ion cyclotron wave dispersion religion including the ion-ion hybrid resonance. Finite-Larmor-radius modification of the wave dispersion relation was also observed, even for ion temperatures of T{sub i} {approx} 1/40 eV. Taking advantage of the relatively high field and long device length of L-4, the existence of the cold electrostatic ion cyclotron wave (CES ICW) was verified. With the arrival of the ACT-1 toroidal device, finite-Larmor-radius (FLR) waves were studied in a relatively collisionless warm-ion hydrogen plasma. Detailed investigations of ion Bernstein waves (IBW) included the verification of mode-transformation in their launching, their wave propagation characteristics, their absorption, and the resulting ion heating. This basic physics activity played a crucial role in developing a new reactor heating concept termed ion Bernstein wave heating. Experimental research in the lower hybrid frequency range confirmed the existence of FLR effects near the lower hybrid resonance, predictedmore » by Stix in 1965. In a neon plasma with a carefully placed phased wave exciter, the neutralized ion Bernstein wave was observed for the first time. Using a fastwave ICRF antenna, two parasitic excitation processes for IBW -- parametric instability and density-gradient-driven excitation -- were also discovered. In the concluding section of this paper, a possible application of externally launched electrostatic waves is suggested for helium ash removal from fusion reactor plasmas.« less

Laboratory experiments are presented simulating aspects of perpendicular ion heating and conic formation that are observed or hypothesized to occur in the terrestrial ionosphere and magnetosphere. Previous laboratory observations of ion conics in the presence of the current-driven electrostatic ion cyclotron wave are reviewed. Field-aligned ion beams, accompanied by beam-generated electrostatic ion cyclotron modes, resulted in perpendicular energization of beam ions and also the heating of background plasma ions. Antenna-launched broadband and narrow-band lower hybrid waves produced considerable perpendicular ion heating and non-Maxwellian “tail” formation. Laboratory results are discussed in light of in situ measurements by the S3-3 satellite and the MARIE sounding rocket.

Low-energy H(+) data with 6-s resolution from the retarding ion mass spectrometer instrument on Dynamics Explorer (DE) 1 have been analyzed to reveal the fine structure at middle altitudes of the nightside auroral region. A new method for deconvolving the energy-integrated count rate in the spin plane of the satellite has been used to derive the two-dimensional phase space density. A detailed analysis reveals an alternating conic-beam-conic pattern with the observed conics correlated with large earthward currents in the auroral region. The strong downward current (larger than 1 microamperes per sq m (equivalent value at ionosphere)) provides a free energy source for the perpendicular ion heating, that generates the ion conics with energies from several eV to tens of eV. The bowl shape distribution of the low-energy H(+) is caused by the extended perpendicular heating. The strong correlation between conics and large downward currents suggests that the current-driven electrostatic ion cyclotron wave is an appropriate candidate for the transverse heating mechanism.

The electrostatic ion cyclotron (EIC) and ion acoustic (IA) waves can be driven unstable by an electron current. The critical drift velocity of the electrons, at which the wave modes become unstable, depends on the parallel and perpendicular temperatures of the electrons and ions, and on the ion mass. We show that in plasma simulations the critical drift velocity for the electrostatic ion cyclotron wave has an additional dependence on the plasma magnetization, Ωe/ωpe. This is negligible for naturally occurring ions, but becomes increasingly important when ion mass mi is reduced below the proton mass (Mp = 1836me). We have solved numerically the dispersion equation for the critically unstable EIC and IA waves for ion to electron mass ratios 40 ≤ mi/me ≤ 1836, and show how the reduction of the mass ratio affects the critical drifts. The temporal and spatial growth rates of the excited waves and changes in the wave behavior when the ion mass is reduced are discussed. It is shown that a careful selection of the ion to electron mass ratio has important consequences with regard to the interpretation of results of two-dimensional numerical simulations of electrostatic wave instabilities, since in certain parameter regimes the EIC wave behavior is strongly altered below a magnetization-dependent ion to electron mass ratio.

It is shown that ion density holes can be generated by a large-amplitude electrostatic ion cyclotron wave on auroral field lines. The rate at which the ion holes are excited is obtained. The presence of ion holes may cause intermittent double layers to be observed in the auroral particle acceleration region. The predicted scale lengths and velocities of the double layers are in agreement with observations.

Electrostatic ion cyclotron wave dispersion relation has been studied in the experiment THORELLO, a steady-state magnetized toroidal plasma, produced in different neutral gases by hot-filament electron emission and acceleration by a bias voltage. Electron temperature and density, evaluated by Langmuir probes, are of the order of 5eV and 1010 cm−3, respectively. The maximum toroidal magnetic field on the axis is about 2kG. The waves are excited by a pair of thin metallic blades, fed with opposite phase by a low power (

This paper presents an investigation of the resonant excitation of the electrostatic ion cyclotron wave at the difference frequency of two microwave beams propagating in a magnetoactive solid state plasma, viz. n InSb. The resonant excitation of the electrostatic ion cyclotron wave occurs when the difference frequency of the two microwave beams and the difference of their propagation vectors satisfy the dispersion relation corresponding to the electrostatic ion cyclotron wave. For typical plasma parameters of n InSb and microwave beams of power densities 1 MW cm−2, the power density of the excited ion cyclotron wave is 0.40 kW cm−2 when external magnetic field is 1.46 kG ( Ω c ω ) = 0.1) . The power density of the excited ion cyclotron wave increases with the magnetic field. This study may provide new means for the characterisation and diagnostic of semiconductors.

This paper presents an investigation of the nonlinear interaction of a Gaussian electromagnetic (EM) beam with an electrostatic ion-cyclotron wave in a collisionless hot magnetoplasma. The EM beam is assumed to be propagating perpendicular to the static magnetic field in the ordinary mode. ON account of the Gaussian intensity distribution of the EM beam in a plane, transverse to the direction of propagation, a dc component of the ponderomotive force becomes finite and leads to the modification of the background electron and/or ion density. This leads to the coupling of the electrostatic ion-cylotron wave with the pump EM beam. This coupling is so important that it may lead to the focusing of the electrostatic ion-cylotron wave and under certain conditions may lead to Brillouin scattering of the EM beam.

Two modes of electrostatic ion cyclotron waves excited in an ion beam plasma system are observed. One of these modes has a sharp and strong spectrum and its dispersion characteristics coincides with one of the backward electrostatic ion cyclotron wave with respect to the propagating component parallel to the magnetic field, the other has a broad spectrum and its dispersion characteristics coincides with one of the forward electrostatic ion cyclotron wave. These excited backward and forward waves occur due to the absolute and convective instabilities. And the transition between two instabilities is observed depending on system parameters. Also, the experimentally obtained temporal and spatial growth of these instabilities are compared with the theory of the weak beam approximation.

Two distinctly different plasma wave modes with structure related to the ion cyclotron frequency, ωci, have been detected by instruments onboard the S3-3 satellite. The harmonic frequency structure with respect to ωci is different for each mode and the two modes exhibit different values of phase coherence. One referred to as the electrostatic ion cyclotron wave has already been discussed extensively in the literature. The other, the ion cyclotron harmonic mode, is discussed in detail here for the first time. This mode has been produced in the laboratory by a perpendicular ion beam and in fact is found to correlate with energetic ion distributions peaked near 90 degrees (ion conies) in the S3-3 data set. The observations are compared favorably to a theory for electrostatic waves with wave vector nearly perpendicular to the magnetic field, in the presence of a perpendicular ion beam.

The theory of the plasma heating by the use of an electrostatic ion cyclotron wave is presented. It provides the optimum heating condition as the interrelation between the plasma density and the r f frequency. An experiment is carried out based on the theoretical prediction and the result agrees with the theory. The feedback control of the heating is also carried out with the afterglow plasma.

The authors examined the parametric decay instability of the linearly unstable electrostatic ion cyclotron wave in an ion beam-plasma system which decays to an ion acoustic wave and a linearly stable electrostatic ion cyclotron wave. They have derived a set of equations which represent this mechanism, and obtained numerical results of the temporal evolution of the amplitude of the related wave and distortions of the velocity distribution function. The beam distortion begins to occur at the stage of linear instability and becomes large at the stage of nonlinear instability. Ion heating of the plasma occurs only at the stage of nonlinear instability. These large distortions of the ion beam and ion heating of the plasma are caused by the deceleration of the ion beam.

Experimental results of ion heating by the use of an electrostatic ion cyclotron wave are presented. When a plasma is composed of several ion species, it is possible to heat the desired one by selecting the frequency of the externally applied r.f. field. A theory of the r.f. plasma heating including the multiple ion species is also presented. A computation carried out for the appropriate experimental parameters agree with the experimental results.

An electron beam modulated near the lower-hybrid frequency is injected into a target plasma immersed in a longitudinal magnetic field. The parametric excitation of the electrostatic ion cyclotron wave and lower-hybrid wave is observed. The threshold and the excited wave potentials are measured by the use of a capacitive probe with a small tip capacitance. Substantial heating of ions and electrons is observed with growth of the instability. Such a rapid heating of ions is ascribed to the electrostatic ion cyclotron wave.

The nonlinear shift of the ion gyrofrequency by the electrostatic ion cyclotron wave is shown to detune the resonance between the ion cyclotron wave and the ion drift wave, thereby stabilizing the drift cyclotron instability. Solutions of the resulting wave equation are shown to exhibit nonlinear oscillations.

A three-dimensional nonlinear Schrüdinger equation for an electrostatic ion cyclotron wave coupled to an ion-acoustic wave in a collision-free plasma consisting of cold ions and two-temperature electrons is derived using the reductive perturbation method. It is shown that a range of wavenumbers corresponding to the instability of a plane electrostatic ion cyclotron wave against a two-dimensional modulation depends on the ratio of temperature of hot and cold electron components.

It is suggested that the highly structured auroral arc is caused by a current-driven laminar electrostatic shock oblique to the geomagnetic field. Electrons are accelerated by the potential jump associated with the shock. The shock is assumed to be confined to a plane. Self-consistent solutions to the Poisson-Vlasov systems are calculated for the electrostatic potential. Adiabatic theory is used to calculate the ion number density in terms of the electrostatic potential and its derivatives. The electrons are assumed to be highly magnetized so they can only move parallel to the magnetic field. Solutions are exhibited for two plasma models: (1) streaming electrons and a two-temperature distribution of ions and (2) streaming electrons and ions and thermal electrons and ions. In the latter model, solutions can be obtained for an arbitrary potential jump across the shock. The shock is identified with the linear electrostatic ion cyclotron wave, and stability of these waves is examined to determine conditions for the formation of oblique shocks. Finally, the theory is discussed in the context of the magnetosphere, and possible model shocks are exhibited and discussed in terms of auroral arc formation.

Three-dimensional nonlinear Schrodinger equation for an electrostatic ion cyclotron wave coupled to an ion acoustic wave is derived with the use of the reductive perturbation method. Electrons are assumed to obey the Boltzmann law under the influence of the electrostatic potential. Cold fluid equations are used for the ions. Instability of a plane electrostatic ion cyclotron wave against a two-dimensional modulation is investigated and the unstable regions are graphically plotted in the wavenumber space.

dc and ac plasma-density and vector-electric-field detectors on a polar orbiting satellite have measured spatially confined regions of extremely large (\ensuremath{\sim}\textonehalf{} V/m) electric fields in the auroral zone at altitudes below 8000 km. Such regions frequently have double structures of opposing electric fields containing characteristic and different wave spectra internal and external to themselves. These structures are identified as paired electrostatic shocks which are associated with electrostatic ion cyclotron wave turbulence.

Ion acceleration of a plasma in a nonuniform magnetic field by an rf field is investigated. The ions are accelerated along the axis of the magnetic line due to the µ∇ // B force, where µ is the magnetic moment of an ion of which energy is increased through cyclotron damping of electrostatic ion cyclotron wave and ∇ // B is the magnetic field gradient along the axis. Ions are accelerated to about 200 eV at rf electric field of 60 V/cm. The computed results of the dispersion relation of the wave including cyclotron damping agree well with the experimental ones.

Two modes were excited by applying oscillating currents to a small coil surrounding a plasma column in a single-ended $Q$ machine. One of them had the same dispersion relation as grid-excited waves, beyond about half a wavelength from the exciting position. The other was an electrostatic ion cyclotron wave propagating along a magnetized plasma column.

Resonant power absorption of electrostatic ion cyclotron wave energy in a nonuniform magnetic field is calculated following Kuckes' model. The calculation explains the experimental evidence of the large suppression effect on the line cusp loss by the resonant absorption of this wave.

Topside ionospheric instabilities of electrostatic ion acoustic and ion cyclotron waves to field aligned currents in single and multiion plasmas

The complete dispersion equation (including all the electromagnetic terms) for flute like (k/sub ///=0) ion cyclotron instabilities in a high beta plasma is solved using both numerical and analytic methods. A new type of ion cyclotron instability is found which is caused by the coupling of an electrostatic ion cyclotron wave with an electromagnetic ion cyclotron wave. The effect of magnetic field inhomogeneity is found to reduce the growth rate of this instability but does not stabilise it.

Anomalous resistivity in a phase-coherent electrostatic ion cyclotron wave in the region of the auroral electrostatic shocks observed by the S3-3 satellite is considered. It is shown that current-driven shocks and anomalous resistivity will be most important above 5,000 km, where the electron drift velocity is maximized and parallel electric fields are possible. A model for the parallel field based on the dissipation of an Alfven wave pulse by current-driven electrostatic ion cyclotron turbulence is presented. In the model, coherent electrostatic ion cyclotron waves lead to anomalous resistivity by electron trapping, producing parallel electric fields greater than 1 mV/m, and may set up the parallel populations necessary to support oblique electrostatic shocks.

Electrostatic ion cyclotron waves observed in space at altitudes between 5000 and 8000 km often have a sinusoidal form. Occasionally, however, wave forms having a spiky or sawtooth form indicative of steepening are observed. The nonlinear fluid equations which characterize the electrostatic ion cyclotron wave have traveling-wave solutions with sinusoidal, spiky, and sawtooth forms. The wave form depends on the amplitude and phase velocity of the wave.

The backward branch of the electrostatic ion‐cyclotron wave has been observed for the first time. The wave, which was driven by a phased antenna structure inserted in a neon plasma, exists in the parameter ranges 2Ti/mi≪(ω/k∥)2≪2Te/me, nΩi Ωi. Double‐tip probe interferometry data agree with the theoretical dispersion relation. The antenna couples into the wave more readily on the side of the antenna where it has its smallest wavenumber.

We have observed the linear coupling between an electrostatic ion cyclotron wave and an ion acoustic wave near the second-harmonic ion cyclotron frequency for propagation of an electrostatic ion wave along a magnetic field, where the wave number perpendicular to the magnetic field ${k}_{\ensuremath{\perp}}$ exists.

It is noted that small-scale regions of large electric fields have been observed above the auroral zone by the S3-3 satellite. The data from five such electrostatic shocks are examined in great detail. The three higher altitude shocks (all above 5,700 km) are found to be associated with upward-going ion beams, indicating that the potential associated with the shock closed below the satellite to give rise to the parallel electric field required for the acceleration of the ion beam. In all these cases, electrostatic ion cyclotron waves are found to be adjacent to the shock and to extend throughout the upward-going ion beam region. The lack of noticeable Doppler shift in the electrostatic ion cyclotron waves in association with large convective drift velocities is seen as indicating that the wavelength of the electrostatic ion cyclotron wave can be several kilometers and that the potential difference within the wave can be on the order of 100 V.

The ion cyclotron drift wave (ICDW), which is the mode coupled between the electrostatic ion cyclotron wave and the drift wave, was investigated by experiments and calculations. The calculated dispersion relations for the m=1 mode show that the mode coupling becomes stronger with increasing |κ| (where κ=dn/dr/n) and a resonance aroud the ion cyclotron frequency changes to a cutoff when |κ| exceeds the azimuthal wave number k y. A simple method to control the radial density distribution is proposed and is confirmed to be varied to a considerable extent. Ion cyclotron drift waves for the m=1, m=-1 and m=2 modes have been excited externally with controlled values of |κ|. The measured dispersion relations agree with the theoretical predictions.

The effects of neutral-particle collisions on electrostatic ion cyclotron instability are analyzed. Experiments were conducted in the Q machine of Motley (1975) with a cesium plasma in which the neutral gas pressure in the main chamber varied from about 5 microtorr-10 mtorr. The relation between electrostatic ion cyclotron wave amplitude and frequency and neutral argon pressure is examined. It is observed that over the full range of neutral pressure the frequency changes by less than 10 percent and the ion cyclotron waves continue to be excited and reach amplitudes of at least several percent at values of the neutral pressure where the ion-neutral collision frequency/ion gyrofrequency is about 0.3.