The paper presents the Gamma-4 four-module electrophysical facility project developed for radiation physics research. For this facility, we have developed and tested a typical module which, with a matched load, generates an electrical pulse with voltage and current amplitudes of up to 2 MV and 750 kA, respectively, and with a half-height duration of 60 ns. 700 shots were performed which conformed the operating parameters and reliability of the module. Layouts of the facility for the modes of synchronous (with accuracy of ±3 ns) operation of the modules with vacuum electron diodes and with a current summator to generate soft x-ray pulses have been developed.

A synchronization system for the Gamma-4 four-module electrophysical facility has been developed. It has been shown that the synchronization system should provide triggering (with precision not worse than ±3 ns) of the high-voltage gas-filled trigatron-type switches of the facility modules (144 spark gaps with an operating voltage of 1 MV), the pre-pulse switches of the modules (24 spark gaps with an operating voltage of 3 MV) and eight Arkad’ev-Marx generators (40 spark gaps with an operating voltage of 100 kV).

The accelerating tube of Gamma-4 electrophysical facility standard module is presented. This accelerating tube is a component part of the energy transmission system of the module which provides delivery of the high-voltage electric pulse from the forming system output to the load unit. A specific feature of the tube design is the use of a dielectric lens to equalize the potential over the surface of the sectioned insulator. The lens made it possible to lower the electric field strength by 30% in the region of the most stressed dielectric rings, thus reducing the probability of the insulator breakdown. To increase the resource of the tube, its dimensions were selected based on the calculated average electric field intensity over the insulator surface equal to 55 kV/cm. The inductance of the tube was 87 nH. 230 shots of the Gamma-1 accelerator were performed using the proposed accelerating tube with an insulator voltage of 2.7 MV. No electrical breakdowns of the insulator were observed in these shots.

RFNC-VNIIEF is developing a four module electrophysical facility “Gamma-4” (2 MV, 3 MA, 60 ns), meant for generation of powerful bremsstrahlung radiation pulses (BR). One of the basic modes of the facility operation is a mode of each module operation with its autonomous vacuum diode. The present work is concerned with electric characteristics of a self-magnetic-pinch (SMP) diode of the typical module of “Gamma-4” facility - pulsed electron accelerator “Gamma-1”. In all there were performed 20 shots of “Gamma-1” accelerator at 0.9 MV charging voltage of its forming system lines. In the experiments the SMP diode with a hollow cathode with 168 mm output diameter was used. The diode impedance was adjusted by changing the accelerating gap between a cathode and a target within the range of 4 up to 14 mm. It is shown, that when changing the diode impedance within the limits from 1.3 up to 4.0 Ohm on the typical module of “Gamma-4” facility there can be implemented operation modes of BR pulse formation with boundary quantum energy 0.9 up to 2.0 MeV.

For the last few years in INRP RFNC-VNIIEF the works on development of a multi-module «Gamma» facility have been conducted. An important part of each module is a pulse transmission system (PTS), providing transportation of a high-volt electromagnetic pulse (~2.3 MV, ~60 ns) to a diode load, positioned at an angle of ~80° to the axis of a module's forming system. Basic PTS units: a water-insulated transmission line (WTL), having a bended section, a vacuum insulator stack and a magnetically-insulated transmission line (MITL). At the first stage an experimental sample of PTS with diameter 0.65 m was studied. Performed studies allowed a conclusion that the given experimental PTS sample did not possess enough electric strength, what was a reason for electric breakdowns in the bended section of WTL. Reasons for breakdown occurrence were analyzed; conclusions were made on the necessity for increasing PTS diameter. As a result a PTS version with diameter ~1 m was developed. This paper presents results of the experimental studies as a part of the facility module. Totally 200 shots of the module were performed with given PTS at different charge voltage of its forming lines. Reliable and steady operation of all PTS units, as well as correspondence between output module parameters and their calculated values were proved. When using PTS, without MITL in the module diode load, with impedance ~3 Ohm the pulses with power 1.5 TW and total electron energy in a pulse ~80 kJ were obtained. When using PTS with cylindrical MITL of 1.6 m length, the pulse power was ~1.4 TW.

A movable electrophysical capacitor installation with a 250-kJ maximum bank energy, which generates intense neutron pulses, is described. A current pulse generator with a capacitive energy storage forms the basis of the installation. When the initial voltage at the capacitor bank is up to 35 kV, the installation ensures a flow of current pulses with amplitudes of up to 2 MA in a gas-discharge plasma-focus chamber, which is filled with an equal-component deuterium-tritium (DT) mixture. Under these conditions, the chamber is capable of repeatedly generating single fast-neutron pulses with an energy of 14.1 MeV, a duration of ∼70 ns, and an integral yield over 1013 neutrons/pulse.

The accelerating tube of "Gamma-4" pulsed power facility module is presented. The facility is now being built at RFNC-VNIIEF. The accelerating tube is the part of pulse transmission system of the module. This system provides high-voltage electric pulse delivering from forming system output to the diode load. The specific feature of a tube design is using of dielectric lens for better grading of electric field stress distribution over vacuum insulator surface. Using the lens made possible to lower electric field stress by 30% and reduced insulator flashover probability correspondingly. The dimensions of the tube were determined by average electric field stress values that not exceed 55 kV/cm. The inductance of the tube is 87 nH. 230 shots were done with accelerating tube with the voltage on insulator up to 2.7 MV. No electric breakdowns of insulator have been observed in these shots.

Описана передвижная электрофизическая конденсаторная установка с максимальным запасом энергии в батарее 250 кДж, генерирующая интенсивные импульсы нейтронов. Основой установки является генератор импульсов тока с емкостным накопителем электрической энергии. При начальном напряжении на конденсаторной батарее до 35 кВ установка обеспечивает протекание в газоразрядной камере с плазменным фокусом, наполненной равнокомпонентной дейтериево-тритиевой (DТ) смесью, импульсов токов амплитудой до 2 МА. При этих условиях камера способна многократно генерировать одиночные импульсы быстрых нейтронов с энергией 14.1 МэВ длительностью 70 нс и интегральным выходом более 1013 нейтронов/импульс.

There presented is a brief review of I-3000, STRAUS, STRAUS-2 and LIA-10M accelerators produced in VNIIEF over the period from 1981 to 1994. All the installations function in the mode of single pulses. Their distinction consists in using the systems of forming high-voltage pulses on the basis of stepped forming lines. Such installations formed of line sections of a similar electrical length with a stepped character of impedance variance provide a high efficiency and as a result of wave processes increase for a several time the output voltage as compared to the charge voltage of lines. The limiting energy of accelerated electrons for the created accelerators lies within the range from 2.3 to 25 MeV, beam current amplitude – from 20 to 50 kA, current pulse width at half-height – from 16 to 40 ns. The basic characteristics of each accelerator are presented. PACS numbers: 29.17.+w; 84.70.+p

The procedure of the device under HF heating and turbulent liquid cooling displacement analysis by means of existent program code is presented. The spatial computational cell size and other requirements ensuring the needed computational accuracy are formulated. In order to illustrate the procedure developed an example analysis of the Electron Resonance Accelerator of a mean beam power up to 300 kW cooling efficiency and deformation is provided.

The results of development and study of Marx generator with output voltage of 1 MV and stored energy of 80 kJ are reported. The measured value of generator inductance is ~ 1.3 μH, the measured effective ohmic resistance ~ 1 Ohm.

This paper presents a project on a CW high-power electron accelerator. The main part of the accelerator consists of half-wave coaxial cavity resonator. The increment of electron energy is reached by repeated passing of an electron beam via full diameter of the cavity in median plain dividing its bulk into halves. Successive redirection of the electron beam into the cavity is performed by means of two rotary magnets. These magnets are placed outside the cavity. Main parameters of the accelerator are as follows: electron beam energy 1.5...7.5 MeV, average beam power above 300 kW, operating frequency 100 MHz.

The characteristics of oil-insulated 8-stage Marx generator aimed at charging water-insulated line of STRAUS-R electron beam accelerator are presented. Two IEPM-100-0.4 capacitors are installed in each stage. Switches in the first three stage are 100-kV gas-filled trigatrons while in other stages - two-electrode trigatrons. Operation delay time is 108 +/- 5 ns at electric strength reserve of each switch being equal to similar to 80%. The circuit inductance is similar to 1.4 mu H.

The electric circuit, design, and characteristics of a shielded oil-insulated Marx pulse-voltage generator (PVG) with a stored energy of 32 kJ and an output voltage of 800 kV are described. The PVG charges a water-insulated forming line of the STRAUS-R accelerator of a pulsed electron beam to 700 kV within a time of <1 µs. Two И ЭПM-100-0.4 УXЛ 4 capacitors are installed in each of its eight stages. The switches of the three first stages are 100-kV trigatrons filled with a 40% SF6 + 60% N2 gaseous mixture to a pressure of 0.7 MPa. The switches of the other stages are two-electrode spark gaps. The PVG-operation delay time is 108 ± 5 ns at a breakdown-strength margin of each spark gap of ∼80%. The PVG-circuit inductance is ∼1.4 µH. The overall dimensions of the PVG's steel tank are 2400 × 800 × 800 mm (without an output device); the PVG mass is 1700 kg.

A large-scale prototype of the PHOS electromagnetic spectrometer, which is part of the ALICE detector, has been built and tested. This prototype has 256 detector channels and is operated at −25°C. Each detector channel is a lead-tungstate crystal coupled to an Avalanche Photo-Diode with a low-noise preamplifier. The prototype includes a 16×16 crystal matrix, photo-detectors, analog and digital electronics, a thermo-stabilized cooling system, a light-emitting diode monitoring system, and a charged-particle detector acting as veto counter. Results of measurements using electron and hadron beams of the CERN PS and SPS accelerators are discussed, and the performance of the prototype is evaluated.

Basing on the developed in RFNC-VNIIEF technology of stepped forming lines a high-power nanosecond accelerator of electrons STRAUS-R has been created to produce single X-ray pulses in the mode of electron beam focusing on a target. The accelerator provides a focus spot ≤4 mm in diameter on a target and maximum X-ray dose of 0.27 Gy (Si) at 1-m distance from the output flange. The boundary energy of electrons is 3.0-3.5 MeV, the electron beam current ≤60 kA and X-ray pulse width ≤50 ns. The description of the accelerator and results of its experimental investigation are given.