A new vacuum-insulated tandem accelerator capable of producing a 5-mA proton beam with energy up to 2 MeV was used to produce a mono-energetic beam of 9.17-MeV gamma rays from the resonant production reaction, 13C(p,γ)14N, at 1.76 MeV. A graphite target enriched with 13C capable of withstanding the proton beam power was designed and fabricated. The 9.17-MeV gamma rays were subsequently resonantly absorbed in 14N via the inverse reaction, 14N(γ,p)13C. The data acquisition system to measure the resonance absorption in nitrogen includes a BGO detector and a goniometer and collimator assembly that rotate around the axis produced by the intersection of the proton beam and the production target. The accuracy of rotation of the detector around the target is approximately 0.1°. The results of the resonance gamma ray absorption measurements are presented to demonstrate the feasibility of the method to sensitively and selectively detect high concentrations of nitrogen, comparable to those found in most explosives.

The results of experiments on generating of resonance gamma-quanta using vacuum insulation tandem accelerator (VITA) are presented. The accelerator is able to produce proton beam with particles energy up to 2 MeV and 5 mA current. The resonance gammas have generated in the carbon target enriched with C-13 isotope with help of C-13(p,gamma)N-14 nuclear reaction. Registration of resonance gamma-quantas is carried out by goniometer and collimator assembly, that capable to be rotated around the target with 0.1 degrees accuracy. The experimental results on absorption of resonance gamma-quanta with energy 9.17 MeV are presented.

The design of a tandem accelerator with vacuum insulation intended for obtaining a proton beam with an energy of 2.0 MeV and a direct current of several tens of milliamperes is described. Calculated and experimental data obtained in tests of both a glass-ceramic feedthrough insulator for a voltage of 1.0 MV and high-voltage vacuum accelerating gaps with electrodes of area of tens of square meters are presented. Issues of optimizing high-voltage aging of the tandem in the cases of its complete and partial breakdowns are considered. The first experimental results of tests of the breakdown strength of individual high-voltage elements and the tandem as a whole are presented.

The results of the tandem commissioning as initial high voltage tests and beam injection experiments on BINP proton tandem-accelerator are given. The accelerator is intended to be used in facilities generating resonant gamma rays for explosives detection and epithermal neutrons for boron neutron-capture therapy of brain tumors. A magnetically coupled DC voltage multiplier derived from an industrial ELVtype electron accelerator is used as a high voltage source for the accelerator. A dc high-current negative ion source has been developed for injection into the tandem. In the tandem accelerator there is set of nested potential electrodes with openings which form a channel for accelerating the negative hydrogen ion beam and subsequently accelerating the proton beam after stripping in the gas target. The electrodes are connected to a high voltage feedthrough insulator to which required potentials are applied from the high voltage power supply by means of a resistor voltage divider.

УСКОРИТЕЛЬ-ТАНДЕМ С ВАКУУМНОЙ ИЗОЛЯЦИЕЙ КАК ОСНОВА МЕДИЦИНСКОГО КОМПЛЕКСА ДЛЯ ЛЕЧЕНИЯ ЗЛОКАЧЕСТВЕННЫХ ОПУХОЛЕЙ МЕТОДОМ БОРНЕЙТРОНОЗАХВАТНОЙ ТЕРАПИИ И ТАМОЖЕННОГО КОМПЛЕКСА ДЛЯ ДИСТАНЦИОННОГО ОБНАРУЖЕНИЯ ВЗРЫВЧАТЫХ ВЕЩЕСТВВ статье описана конструкция и области применения оригинального протонного ускорителя с вакуумной изо

An electrostatic tandem‐accelerator with 2.5 MeV 10 mA proton beam is under development at BINP. One of the important accelerator parts is a target that converts the half energy accelerated negative hydrogen ions into the proton beam. In the tandem accelerator an argon stripping target with 1 cm tube diameter and 40 cm tube length will be used. To reduce argon flux from the target to accelerator gaps a gas recirculation by turbomolecular pump installed in high voltage electrode is provided. Processes of plasma production and ultraviolet emission due to target ionization by fast ions and stripped electrons are considered in the report.

To solve problems of boron neutron capture therapy in the BINP an electrostatic tandem accelerator with vacuum insulation on proton energy of 2.5 MeV and current of tens mA is developed. The experimental results on the study of distributing concentration of gas molecules emerged from the charge-exchange target to the vacuum volume are performed in the paper. The vacuum characteristics of the system on the pumping of different gases of the target both external turbo-molecular and internal cryogenic pumps are given. The experimental results on the estimation of stripping gas effect emerged from the target to the vacuum volume on electrical strength of 45 mm of high voltage vacuum gap are performed. The area of electrodes is about of 0.7 m.

As part of a program aimed at the development of a vacuum-insulation tandem accelerator with a proton energy of 2.5 MeV and a current of several tens of milliamperes, the distribution of the density of the gas released into an evacuated volume by the stripping target was measured. The results from high-voltage tests of a coaxial 45-mm vacuum gap with an electrode area of 0.71 m2, obtained at various values of residual pressure, are presented.

The status of the design work on an electrostatic tandem-accelerator with vacuum insulation for 2.5 MeV protons and up to 40 mA constant current is reported. This machine is to be used for solving problems of neutron therapy and the detection of explosives by nuclear-resonance absorption of γ-rays.

Theoretical and experimental results on the development and testing of a system of high-voltage vacuum accelerating gaps with electrode areas of several tens of square meters are presented. The energies stored in individual gaps may reach several tens of joules. The work is carried out as part of a program aimed at the development of a tandem electrostatic accelerator with vacuum insulation designed for a proton energy of 2.5 MeV and current of several tens of milliamperes. Optimization of the high-voltage part of the tandem with respect to the overvoltage arising in high-voltage elements of the tandem during its full or partial breakdown and to the energy stored in capacitors formed by the vacuum accelerating gaps and related elements of the tandem is considered. Experimental data on the electric strength of a 45-mm vacuum gap for different energies released in the breakdown are presented. For an electric field intensity of several tens of kilovolts per centimeter, the value of the field-emission current in a high-voltage gap with electrodes of a large area is estimated.

A cascade accelerating-voltage generator with inductive coupling and parallel power supply to the cascades is examined. The basic parameters and dimensions of a generator for a voltage of 500 kW and power 10 kW are presented.

Original 2 MeV proton tandem accelerator with current 10 mA for monochromatic 9.17 MeV gamma-quantum production on Carbon-13 target for contraband detection is described. The tandem is supplied by a powerful sectioned rectifier from ELV type industrial accelerator providing high stability of the proton beam in the region of maximum gamma rays production at protons energy 1.75 MeV. Variants of gas stripper system and design of 100 kW Carbon-13 target with liquid metal cooling are presented. Also the results of optics calculation for focussing on stripper of 10 mA compensated H - beam with heterogeneous density and transverse energy about 1 eV are given.

Original 2.5 MeV, 40 mA proton tandem accelerator for the neutron therapy facility is described. The results of computer simulations of high current hydrogen negative ions beam transmission through the special geometry of potential electrodes with vacuum insulation are presented. The results of experiments with prototype vacuum insu- lation tandem accelerator are given also. Various charge- exchange targets are considered. Namely, targets are gas target with outward pumping, gas target with pumping inside of high-voltage electrode.

The results of an experimental study are described: the breakdown strength of gas gaps in the geometry of ring axial protective spark gap switches of accelerating tube and gas gaps of a high-voltage forming line in the geometry of coaxial cylinders. Measurements were performed with a SF6 gas pressure below 1.2 MPa, electrode areas less than 2.73 m(2), and de voltages no higher than 1.0 MV.

Overvoltages across elements of an accelerating tube, arising upon breakdown of one of the tube sections or when the corona-discharge current flows from the accelerating tube high-voltage electrodes, are analyzed. Methods for decreasing the overvoltages are demonstrated. Overvoltages across elements of the accelerating tube designed at the Budker Institute of Nuclear Physics are calculated for various diameters of the vessel containing the tube, different values of the corona-discharge current flowing from the accelerating tube elements, and different resistances of a resistive voltage divider.

The transverse corona-discharge current that causes overvoltage across individual sections of an accelerating tube is experimentally investigated. A corona-discharge current from high-voltage tube electrodes is obtained as a function of voltage for a tube placed in tanks of various diameters. Accelerating tube protection against breakdowns is discussed, and corresponding experimental results are presented.