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A new method of intense relativistic electron beam modulation at frequencies up to ∼1 GHz is suggested. Current modulation is provided by using the azimuthal magnetic field of the beam to control the beam reflection from the magnetic mirror. The results of computer simulations for a 2-MeV, 20–50-kA beam are presented.

Paper describes the first experiments on generation of 4-mm radiation in two-channel planar FEM with combined electrodynamic system carried out at the ELMI-device. The results of spectral and calorimetric measurements are presented and discussed.

In experiments at ELMI-device (BINP, Novosibirsk) the operation of 4-mm free electron maser (FEM) with two dimensional distributed feedback was demonstrated [1, 2]. These results gave a base for development multichannel planar FEM with 2-D distributed feedback [3]. In case of two channels jointed by special waveguide 2-D distributed feedback can be also used for two stage generation of submillimeter radiation exploiting an intercavity scattering scheme [3]. As the first step on studying of two stage generation we performed the experiments on simultaneous generation and transport of two intensive sheet electron beams. We modified the geometry of a ribbon accelerator diode at the ELMI-device and realized simultaneous generation of two sheet beams with the following parameters: the electron energy − 0.8 MeV, the total current of each beam - 3 kA, the cross section 0.4×7 cm and the pulse duration - 3 mcs. These sheet beams were transported on the length 1.3 m in slit vacuum channels with cross section 0.95×9 cm in the guiding magnetic field 1.7 T [4]. Next step of this series of experiments is devoted to realization of the two stage scheme. The paper presents results of the experiments and theoretical analysis of a prospect of the two stage scheme for THz pulses generation.

Essential progress was achieved in experiments on heating the dense plasma in the multimirror trap GOL-3 by high power relativistic electron beam in last few years. The beam parameters at the experiments were the following: electron energy ∼1 MeV, beam current ∼25 kA, beam current density in plasma ∼2 kA/cm2, pulse duration about 10 ms, total energy of the beam pulse ∼150 kJ [1]. Due to the high level of the current density and effect of a novel mechanism of ion heating the temperature of ions reached 2−3 keV at the electron temperature about 3 keV for the plasma density ∼1015 cm−3 [1]. Energy confinement time of the plasma in these experiments has reached the level of 1 ms. The basic condition of such parameters achievement is anomalously low electron thermal conductivity along the trap axis which is provided by small scale Longmuir turbulence developing as a result of two-stream instability [2]. In order to analyze a prospect of further increase of plasma parameters for reaching a fusion area, to elongate the beam pulse duration was decided. As the first step on solving this task we are performing the experiments at the accelerator U-2 on 1.5 fold increase of the E-beam duration. To investigate in more details the process beam-plasma interaction we carry out measurements on temporal dynamics of the plasma electron distribution function in the range of 0–5 keV and on evolution of energy distribution functions of the beam electrons as well. We also measure an electromagnetic radiation gone out from the plasma column as result of transformation of two Langmuir waves in electromagnetic one in strong turbulent plasma. This electromagnetic radiation is measured in the frequency band 210−550 GHz. Results of the pointed experiments and their discussion are presented in this paper.

Essential progress was achieved in experiments on heating the dense plasma in the multimirror trap GOL-3 by high-power relativistic electron beam in last few years. The beam parameters at the experiments were the following: electron energy ~1 MeV, beam current ~25 kA, beam current density in plasma ~2 kA/cm2, pulse duration 9 mus, total energy of the beam pulse ~150 kJ. Due to the high level of the current density and effect of a novel mechanism of ion heating the temperature of ions reached 2-3 keV at the electron temperature about 3 keV for the plasma density ~1015 cm-3. Energy confinement time of the plasma in these experiments has reached the level of 1 ms. The mechanism of fast ion heating is based on the collective ion acceleration along the magnetic field lines produced by high-gradients of the electron pressure in the plasma due to enhanced heating in the mirrors. The basic condition for such mechanism realization is anomalously low electron thermal conductivity along the trap axis which is provided by small scale Langmuir turbulence developing as result of two-stream instability. In order to analyze fusion prospects of such way of plasma heating in the long solenoid trap it is necessary to investigate experimentally the possibility of further increase of plasma parameters by the elongation of the beam pulse. As the first step on solving this task we have performed the experiments at the accelerator U-2 on 1.5 fold increase of the e-beam duration. Results of these experiments are presented in this paper. Conditions for durable generation in magnetically insulated diode, stable transportation and compression in the magnetic field of intense REB found in the experiments, permit us to increase the beam pulse duration from 9 mus to 14 mus with somewhat less energy of the electrons but with the same level of the energy content in the pulse. In the paper we describe the experiments on the diode voltage shaping for better matching of pulse generator with the accelerator diode as well as the results of measurements of the beam cross section by means of X-ray obscure and sectional calorimeter. Also we discuss the directions of future investigations aimed to the increase of the beam parameters in order to obtain (5-10) keV temperature of the plasma confined in multimirror trap.

This paper describes main features of a project on two- stage generation of submillimeter radiation pulses at ELMI-device. In this project one sheet beam will drive 2D Bragg planar FEM in which intensive 4-mm radiation accumulated in the FEM resonator, is used for stimulated scattering on the another sheet beam.

Paper describes main features of a project of an experiment at ELMI-device on two-stage generation of submillimeter radiation pulses. In this experiment two parallel high current sheet beams will be used. Submillimeter waves generation is based on stimulated scattering of mm-waves accumulated in the resonator of a planar FEM-oscillator driven by one of these beams.

Summary form only given. Essential progress has been achieved on GOL-3 experimental facility (Novosibirsk) in recent years. Deuterium plasma with density 1015 cm-3 is heated by relativistic electron beam up to temperatures in order of 2 keV, both for electron and ion plasma components. Neutron output has been obtained for the plasma. The paper presents one possible way to increase neutron output. It can be done if small condensed matter target with density about 1 containing deuterium would be placed into the plasma. Estimations of neutron output for different targets are presented in the paper, obtained by means of numerical simulation. The basis of the calculation model is physico-mathematical model of hot plasma interaction with solid target. Equations of gas dynamics, kinetics of level population of multi-charged ions and radiation transfer in lines and continuum, kinetics of chemical decomposition of target matter or its evaporation are solved self-consistently. Calculations of neutron output for targets of frozen deuterium, lithium deuteride and deuteration polyethylene have been done. Estimation of tritium accumulation in reaction Li3 6 + n0 1 = H1 3 + He2 4 for lithium deuteride target is presented. Neutron output has been calculated for targets with deuterium-tritium mixture as well. Size of target with maximum neutron output has been obtained

Collective interactions of a microsecond electron beam with a plasma and its fast heating is being investigated at the GOL-3-II facility. This activity is mainly directed for production of a hot dense (10/sup 15/-10/sup 17/ cm/sup -3/) plasma in long open trap in order to study the multimirror and "wall" confinement of such a plasma. The plasma that is already obtained and can in principle be obtained in this facility is of interest for a broad spectrum of applications, like controlled fusion, a pulsed neutron source, X-ray flash lamps, UV laser etc. Recent results performed at the GOL-3-II facility are presented. These are beam energy losses, plasma heating and electron and ion temperature measurements.

To provide basic operations of semiconductor and radiation materials technologies, a multipurpose implanter with intense ion beams was developed at the Institute of Nuclear Physics. The generated beamparameters are as follows: ions are H+, O+; C+; the ion energy is up to 200 keV; the beam current is up to 2 mA; and the implantation mode is continuous. The size of the target to be processed can reach 76 × 76 mm2. During the implanter operation, the target chamber vacuum reaches 10−4 Pa. The entire process of target irradiation is fully automated.

The high-power hot plasma stream of E-beam heated plasma in the GOL-3 facility is used for exploratory plasma stream-target interaction experiments under conditions rather typical for the thermal quench phase of ITER tokamak plasma disruptions. The recent experimental results are presented.

In calculating high-current relativistic beams of charged particles moving in electromagnetic fields, it is necessary to take account of the effect of the electric and magnetic self-fields products by the beams themselves. This effect has been modeled on a computer [1, 2]. The present paper describes numerical algorithms contained in the KSI-BESM compiling system [3] which permit the inclusion of a broad class of relativistic problems, taking account of the magnetic field of currents flowing in the metal parts of the device being calculated, and also problems with virtual cathodes.

Strong relativistic electron beams in the microsecond range, with a current density of 1-10 kA/cm/sup 2/, and a stored energy of tens of hundreds of kilojoules can be used effectively for plasma heating in open traps. The authors given the results of numerical calculations of the parameters of beams obtained in diodes with quasiplane and annular cathodes in an external magnetic field. The results of the calculations are compared with the experimental data. The comparison is made for initial times (t less than or equal to 0.4 ..mu..sec), when the change in the accelerating gap due to filling of the diode with plasma is still insignificant. The question of the influence of nonuniformity of emission from the cathode on the amount of current of a plane diode is also analyzed by numerical modeling.

The article is devoted to a verification of the law of similarity in the flow of a rarefied magnetized plasma around a body under conditions which simulate the conditions of flow around artificial earth satellites in the ionosphere. The law of similarity for flow around plates and cylinders of different sizes (R0/ϱi≈0.5–1, V0/Vi≈1.5–2) is confirmed experimentally. It is shown that the patterns of flow around a plate and a cylinder coincide at small values of the parameter δ(δ=R0/zH). The effect of the potential of the bodies on their flow patterns is studied.

A method for determining the spatial structure of a high-power relativistic electron beam is described. Using an absolutely calibrated CCD collector, the thermal-radiation brightness distribution of the beam-collector surface is registered in the visible and near-IR spectral regions and then converted into a spatial distribution of the beam energy deposition in a target. This method is applied at a high specific beam-energy flux (∼1 kJ/cm2), one which causes noticeable erosion of the beam collector.

The GOL-3-II facility was used for the investigation of the interaction of a high-power plasma stream with solids. The experiments allowed the study of the properties of the dense plasma formed in front of materials under action of the fast electrons flowing out the open trap. Target plasma from entrance foil with density 10 16 cm -3 has the expansion velocity 2-4 10 6 cm/c. Explosive-like erosion of the exit graphite receiver was been observed. Formation of a dust cloud is a feature of this phenomenon. Properties of the dusty particles are discussed.

A set of diagnostics for plasma spectroscopy was developed for multimiror trap GOL-3. It includes survey spectrometer with spatial resolution and the high spectral resolution complex for line shape analysis. The systems allow recording waveforms of plasma radiation with spectral resolution of 0.01 nm and measure spatial distribution of line radiation intensity (simultaneously in π and a components). Analysis of radiation spectra was used for investigation of impurities structure and dynamics. Precise measurements of spectral line shape were used for finding the electron density and ion temperature from a line broadening. Description of the equipment and experimental technique as well the recent results are presented in the paper.

Phenomenon of fast heating of plasma ions in the multimirror trap GOL-3 is discovered and explained. An essence of effect is that ion component of the plasma is heated during electron beam injection much faster (at 100 - 1000 times) than due to binary electron-ion collisions. An analysis of experimental results is presented and discussed. A model of fast non-Coulomb ion heating is suggested.

Review of the experimental results for the last two years on study of dense plasma heating and confinement in a long multimirror trap GOL-3 is presented. This facility is an open trap for confineme...

A description of the GOL-3-II facility and the first experimental results obtained on this new device are presented. This facility was constructed as part of the second stage of the GOL-3 programme for studying the interaction of microsecond electron beams with a plasma and its fast heating. The plasma column of the GOL-3-II facility is 12 m in length instead of 7 m for the first stage of GOL-3. The energy content of the capacitive storage for magnetic field supply has been increased from 10 MJ to 15 MJ. This allows us to have a magnetic field of up to 5 T in the homogeneous part of the solenoid and up to 10 T in its end mirrors. The expected key feature of the upgrading is an essential increase in the energy content of the electron beam injected into the plasma. The high-power electron beam generator U-2 is now used for the new beam - plasma interaction experiments with possible beam energy content of up to 0.3 MJ. It is shown experimentally that transportation of a 0.2 MJ electron beam through the 12 m plasma column is possible under conditions of almost full current neutralization. The collective beam - plasma interaction results in a plasma heating of up to 1 - 2 keV electron temperature at density.

Two separate topics on a pellet injection activity at the multimirror trap GOL-3 are presented. The first topic is connected with studies of influence of a high-energy-density plasma on solids. A carbon pellet of 2-mm diameter was injected into the plasma for this purpose. The second discussed topic is a status of works on a cryogenic pellet injector for plasma fueling at GOL-3.

Recent results of the experiments at GOL-3 facility are presented. In present configuration of the device, plasma with a density of 10 14 ÷10 16 cm -3 is confined in a 12-meter-long solenoid, which comprises 55 corrugation cells with mirror ratio B max /B min =4.8/3.2 T. The plasma in the solenoid is heated up to 2-4 keV temperature by a high power relativistic electron beam (∼1 MeV, ∼30 kA, ∼8 μs, ∼120 kJ) injected through one of the ends. Mechanism of experimentally observed fast ion heating, issues of plasma stability and confinement are discussed.

A short review of recent results obtained at the GOL-3-II facility is presented. This facility is an open trap with 12 m long plasma column with a longitudinal magnetic field of 4.5 T in the unifor...

Recent results of experiments on high-energy content E-beam application for plasma heating in a multimirror trap GOL-3 are presented. Conditions for optimal neutralization of injected beam and its stable transport through long plasma column are defined. Effective electron and ion heating of plasma is observed.