[en] Results of experimental investigations of current transport dynamics for a conductivity phase in a microsecond plasma switch (PS), brought into a circuit of inductive storage of 'DUBL' generator, operating under conditions of negative polarity of output voltage pulse with 480 kV; 0,7μH; 0,533 μF parameters, are presented. The carried out investigations using magnetic probes provided to plot time pattern of equicurrent lines in PS, showing faster anolyte current penetration into plasma. It was shown that conductivity phase is characterized by motion in current channel (CC) plasma- a ragion with peak current density on cathode. The main current in CC is transported by electrons but along the full length of PS the share of ion current by the end of conductivity phase constitutes 30%. Maximum transport rate of CC front and ion current front along cathode was observed in the last 50 ns of conductivity phase. Ion current channel density both in current channel and behind it exceeded the value of saturation ion current of preliminary produced plasma

[en] Results of experimental study of dynamics of electron and ion losses in a microsecond plasma switch (PS), carring the short-circuited inductance load and operating with open potential electrode, are presented. Investigations were carried out at 'DUBL' microsecond generator with stored energy of 56 kJ and 300 kA current amplitude in inductive storage. The investigations showed that primary channel of energy losses, limiting microsecond plasma switch impedance, are energy losses: they constitute 70% of all losses under inductive load and 30% during operation with an open cathode. It was shown that ion current in PS attains its peak value by the end of conductivity phase and it does not increase in switch phase. With an open cathode, PS impedance is defined by an electron beam, forming during current switch phase and propagating towards external electrode end. In this high-current electron beam H⁺ ions, accelerated up to 3.5-4.2 MeV energy, and outcoming from PS plasma boundary, were detected

[en] This paper deals with computer simulation of plasma erosion opening switch (PEOS) operation in the context of short-pulse high power ion beam (HPIB) generation in microsecond store systems. The scaling of PEOS parameters and ion diode characteristics with various operating conditions was determined. The simulations showed the best PEOS characteristics for a hydrogen plasma (i.e., the lowest mass) with a high flow velocity and low density, although for some applications a plasma with A/Z > 1 may be preferable. It was shown that the efficiency of HPIB generation in the diode depends on its location relative to the PEOS, the time delay of anode plasma formation, the use of a spiral electrode in the PEOS region, and the use of an arrangement involving an ion return current bypass through the PEOS region. The optimization of the PEOS and ion diode with coaxial configurations and 100 kJ stored in the 600-kV Marx yielded a 16-percent overall efficiency HPIB generation in the diode, with a diode voltage and power of 4.2 MV and 0.42 TW, respectively

[en] The modified hydrodynamic approach is being used to study the characteristics of plasma motion due to magnetic pressure in plasma opening switch. The simulation code differs from the NRL counterpart with dividing of the plasma filled region into N sections and with using the experimentally measured current penetration parameters. The simulation of the switch opening phase is performed in terms of erosion mechanism of magnetically insulated vacuum gap forming. The code includes the circuit data which are regular for the DOUBLE generator operation regimes in the negative polarity of inner (potential) electrode. In the case of typical duration of the conduction phase (900 ns) the minimum needed plasma density was found to be about 10¹⁵ cm^-3. The best fit of conduction current amplitude vs plasma density is I ∼ n^0.23. The calculated characteristics of the switch opening phase were obtained to be very close to the experimental data

[en] The barrel type ion diode with ballistic focusing was designed and tested at the generator MARINA with Microsecond Plasma Opening Switch (MPOS) operating on the level of up to 1 MV voltage and 250--300 kA of stored current. The results of the MPOS-diode circuitry performance tests and ion beam parameters measurement are given

[en] A method for measurement of voltage directly in the gap of a high-current diode is described. The method is based on measurement of bremsstrahlung attenuation in absorbing filters. An algorithm is described for calculation of the bremsstrahlung attenuation on which the method is based. The time resolution was 7 nsec and was determined by the frequency response of the recording apparatus

[en] Direct experimental estimate of the upper limit of the d + d → ³ He + n cross section at deuteron energies below the keV region is obtained for the first time. The experiment was performed at the Pulsed Ion Beam Accelerator of the High-Current Electronics Institute in Tomsk, using high intensity, radially converging deuteron beams, generated during implosion of liner plasma. A two-jet liner made of 17% D₂ + 83% N₂ gas was used, with the inner jet serving as a target. The dd-fusion neutrons were registered by time-of-flight scintillator spectrometers and BF₃ detectors of thermal neutrons placed on polyethylene moderator. The upper limit obtained for the d + d → ³ He + n cross section for deuteron energy 440 eV is σ < 2 x 10^-34 cm² at 90% confidence level. The result demonstrates that liner implosion technique can be used in the investigations of nuclear reactions between light nuclei at ultralow energies, previously not accessible in experiments with classical beam accelerators

[en] The goal of the present investigation is to measure cross sections for the reactions between light nuclei in the energy range 100--2,000 eV using intense nanosecond ion beams produced by means of liner plasma. The experiments of this project will allow unique information on characteristics of nuclear reactions between light nuclei at superlow collisions energies. With classical accelerator it is actually impossible to get accelerated particle beams that are intense enough to measure extremely small cross sections of the reactions in question. Now there are experimental data of pd, dd, dt and tt cross sections at collision energies over 50 keV, 3 keV, 5 keV and 30 keV respectively. Their values fall within the range 10^-30--10^-31cm². According to theoretical calculations, the cross sections for the reactions in question at energies 100--2,000 eV lie in the range 10^-35--10^-48cm², so classical accelerators cannot be used to measure cross sections for these processes at the above energies because of low intensity of accelerated p, d, t beams. In this connection they suggest that highly intense, radially convergent ion beams generated during implosion of liner plasma should be used. Intensity of these beams is about 10²¹ particles per pulse in the given energy range

[en] The numerous experiments of Micro second Plasma Opening Switch (MPOS), carried out in the Institute of Electrophysics during the last decade proved that MPOS is an effective source of charged particle beam of large cross-section. In operation with inductive type of the load more than 60% of the MPOS losses are coupled with ions: at the current level of 200 kA the energy store of the ion beam makes up to 4 kJ; the electron losses in the MPOS are low and located near the downstream portion of the switch. Operation with open end load the MPOS couples 5 kJ with the ion flow and 12 kJ with electrons. Electron beam is composed of two parts: the cylindrical beam, propagation along the axis and radially divergent beam with area bigger than 1 m². With inner location of the anode in the vacuum coaxial the divergent ion beam was generated, having density of 200 A/cm². The MPOS displayed properties of efficient charge particle flows source. By variation of the geometry of electrodes and plasma density they controlled the parameters of the beams in wide range

[en] This paper is devoted to experimental studies of a short-pulse ( 80 ns ) inductive system with a coaxial plasma erosion opening switch (PEOS), operating at the 2-5 X 10/sup 10/ W level. Scalings of the PEOS and ion diode characteristics with different parameters (PEOS plasma density and velocity, PEOS electrode geometry, load impedance, type and strength of an external magnetic field) were carried out. It was seen that for the most efficient energy and power switching to the load by the PEOS, the following conditions are preferable: high velocity and low density of the plasma flow, negative polarity of the inner PEOS electrode, coincidence of the switch current and injected plasma flow directions, the absence of an external magnetic field, and the presence of an additional self-field in the PEOS region. Power enhancement of a factor of 3 and pulse shortening by a factor of 2 were obtained under optimal conditions