The advanced fast ion-dominated high beta plasma is achieved using multi-MW neutral heating beams. To facilitate the diagnostics of this fast ion-dominated plasma, a high-energy and high-current diagnostic neutral beam (DNB) injector was designed and built by the Budker Institute of Nuclear Physics. The DNB injector made active measurements of ion temperature and rotational velocity possible with the help of charge-exchange spectroscopy for impurity ions and, most importantly, for the main ion (deuterium) component. A DNB energy of 40 keV was chosen to assure low beam attenuation in the plasma and to enable spectroscopic measurements along the entire plasma column. The diameter (level 1/e) of the ballistically focused DNB in the plasma is about 8 cm. To achieve a high temporal resolution, unique methods of beam modulation with a frequency of up to 10 kHz were implemented. The achieved high DNB current of 8 A in atomic hydrogen in combination with the beam modulation enables to obtain an acceptable signal-to-noise ratio of the measured spectra.

A 2.5D hybrid model is used to numerically study the interaction of a beam with a current of 2.5–7.5 kA and an electron energy of 345–510 keV and terahertz (364–368 GHz) electromagnetic field. It is shown that Bragg reflectors in an electrodynamic system with an overmode ratio of 49 make it possible to significantly suppress backward radiation and multiply increase the radiation power in the direction of the electron beam. Radiation pulses with a power of up to 330 MW are obtained in calculations with disregard of heat loss in the presence of a guiding magnetic field of 6 T.

An overview of the neutral beam injectors developed at the Budker Institute of Nuclear Physics in Novosibirsk during the last 10 years is presented. These neutral injectors are used for plasma diagnostics, heating and current drive in modern fusion devices with magnetic confinement. An arc or a radio-frequency (RF) discharge generates a plasma in the ion sources of the injectors, and a positive hydrogen or deuterium ion beam is extracted and accelerated by a multiaperture ion-optical system (IOS). The accelerated ion beam is converted into a neutral one in a gas target. The precision multiaperture IOS with spherically concave electrodes provides ballistic focusing of the neutral beam. The high-energy, high-power beam injector based on negative ions, which is currently under development, is described as well. It comprises a RF negative ion source and a wide-aperture electrostatic accelerator separated from the source by a low-energy beam transport line, thereby improving the injector reliability.

Production of neutral beams consisting of the mixed hydrogen isotopes is of interest for the purposes of diagnostics, since it enables us to study the relaxation process of fast ions trapped in plasma using the neutron diagnostics. In addition, the injection of mixed deuterium–tritium beams for heating and sustaining the plasma could greatly simplify the expensive systems for isotope separation in fusion reactors. In this work, the Doppler spectroscopy technique is used to experimentally determine the fractional content of ions with different masses in the ion source beam consisting of the mixed hydrogen isotopes (hydrogen–deuterium beam). The experience acquired in this field is proposed to be further used to optimize the conditions for plasma generation in the ion source in order to obtain an ion beam with the mixed isotope composition and specific characteristics required for various applications.

For plasma heating and stabilization in open magnetic traps, the high-power neutral beam injector with tunable beam energy was developed at Budker Institute of Nuclear Physics. The initial energy of the beam particles is 15 keV, and it can be subsequently increased to 40 keV. In this case, the neutral beam power increases from 1.7 to 3.5 MW. A distinctive feature of this injector is the fact that, as the accelerating voltage considerably changes, the ion beam current remains constant. The injectors based on the ion sources with tunable energy are used in experiments at the C-2W open trap (USA).

A high-voltage negative ion based neutral beam injector is under construction at the Budker Institute of Nuclear Physics. It consists of a negative ion source, a Low Energy Beam Transport section (LEBT), which purifies the beam before acceleration, a multi-electrode single-aperture beam accelerator, a negative ion neutralizer and a magnetic separator with beam energy recuperators. The test stand to study the main injector components, consisting of the negative ion source and LEBT, the high voltage platform and the accelerator with beam transport section was launched in 2019. The initial experiments on the negative ion beam production, acceleration and 180 keV transport were tested. The power load to the acceleration tube electrodes and the data on the transported beam parameters, measured at the several positions and at the beam dump calorimeter are presented. The beam transport efficiency as a function of various ion source and LEBT parameters are presented and discussed.

A prototype of a powerful high-voltage neutral beam injector, based on acceleration of negative hydrogen ions and their neutralization, is under development at Budker Institute of Nuclear Physics (BINP). The design of the BINP high-voltage injector includes several innovative components, important for injector operation stability and overall efficiency. It includes a multi-aperture long-pulse surface-plasma negative ion source with thermostabilized grid, ithe magnetic system with concaved field lines in the ion-optic system (IOS) and the distributed cesium deposition system. The injector scheme incorporates a wide-aperture low-energy beam transport (LEBT) section, plasma target for negative ionneutralization, and recuperators of non-neutralized ions. Several test stands were constructed at BINP for injector component studies. This paper describes the results of experiments on negative ion beam production, transport through LEBT, ion acceleration to energy up to 240 keV and transport through the high voltage beam transport (HEBT) section to the distance ∼10 m from the source. The parameters of the transported beam, which were measured at several points along the beam line and at the beam dump calorimeter, are presented. The beam transport efficiency as a function of various ion source, LEBT and HEBT parameters is measured and compared with the calculated values. The results dof plasma neutralization target study are presented as well.

In the Budker Institute, the CAT (Compact Axisymmtric Toroid) experiment is being prepared for obtaining a plasmoid with high diamagnetism in axially symmetric magnetic field. Reverse of magnetic field in the plasmoid is also possible in this experiment. The experiment is based on injection of powerful focused neutral beams with extremely large neutral power density in the plasma. Two neutral beam injectors with the energy of hydrogen atoms of 15 keV will be used in the experiment. The neutral beam power of each injector is 2 MW, pulse duration is 5 ms. In the ion source of the injector, plasma emitter is produced by plasma jets from four arc plasma generators. Proton beam with current up to 170 A is formed by multi-slit three-electrode ion-optical system with ballistic focusing. Measured angular divergence of the formed beam along the slits is 10 mrad, divergence in the direction across the slits is 35 mrad. The injector is equipped with a neutralizer, bending magnet, residual ion dump, calorimeter, high speed pumping system with titanium arc evaporation.

Negative-ion based neutral bean injector is under development at Budker Institute of Nuclear Physics. It's essential feature is beam transport from the multiaperture source to a single-aperture accelerating tube through a low energy beam transport line (LEBT). This scheme permits to purify the beam from the co-streaming fluxes of fast hydrogen atoms, gas molecules, cesium vapor. As a result, the loading on the accelerating tube by harmful co-streaming and secondary particles is considerably reduced. It will enable more stable operation of the negative ion beam accelerator. Experimental study of long-pulsed 0.8-1.2 A, 85-100 keV negative ion beam formation and transport through the LEBT to the distant calorimeter is described. The parameters of the transported beam were electrically measured in the LEBT center at distance 1.6 m by the movable Faraday cup and at the LEBT exit (at distance 3.5 m from the source) - by the multisection beam calorimeter. The efficiency of beam transport vs various source and LEBT parameters is discussed.

High-voltage negative-ion based injector is under development at Budker Institute of Nuclear Physics. Production and transport of negative ion beam are studied at separate test stand, consisted of a long-pulse RF surface plasma source and a low energy beam transport line (LEBT). Deflecting magnets and two high speed 105 Ls cryopumps, that are installed in LEBT, purifies the beam from the co-streaming tluxes of electrons, hydrogen atoms and molecules, and cesium vapor. Paper presents the experimental results on 1 A, 90 keV II- beam production and transport through the LEBT to the multisection calorimeter installed at distance 3.5 m from the source. The parameters of the transported beam were measured at distance 1.6 m by the movable Faraday cup and at the LEBT exit by beam calorimeter. The efficiency of beam transport vs various source and LEBT parameters will be presented and discussed.

An overview of studies into the physics and technology of ion and neutral beams carried out at the Bunker Institute of Nuclear Physics, SB RAS since 1960 up to now is presented. These studies were initiated by Academician G I Budker for the charge-exchange injection of particles into storage rings. Sub-sequently, a whole series of ion sources were created and particle beams were produced for applications in accelerators and plasma devices for plasma heating and diagnostics.

The 15 kV, 2 MW neutral beam injector (NBI) was developed for C-2U magnetic trap experiments. Important part of the NBI is efficient pumping system which provided a good vacuum condition during beam pulse. The pressure rise during the NBI operation and accompanying gas flow to the fusion device is a negative factor both for the beam transportation and for fusion experiment. The high-speed pumping system based on four Ti-bar arc-discharge evaporators placed inside LN2-cooled volume was developed and successfully used in vacuum chamber of the 2 MW NBI. The results of calculations and tests are presented both at the room and at the LN2 temperatures of the gettered surface. Achieved pumping speeds are about 10(5) and 4.10(5) l/s correspondingly. Also gas capacitance of the gettered surface and conditions of uniform gettering were established.

We have described the results of numerical investigations of different versions of a three-electrode elementary slit cell for the formation a hydrogen ion beam with a relatively low energy and a high emission current density. The version of the cell chosen from the results of these investigations makes it possible to obtain a hydrogen atom beam with an energy of 15 keV, an ion current density of ~500 mA/cm2, and an angular divergence of 24 mrad.

The paper describes experiment devoted to the field reversal in a mirror trap with neutral beam injection, which is planned for realization now in Budker Institute. The technical details of experimental device and expected plasma parameters are discussed. In accordance with theoretical predictions, parameters of experimental facility (neutral beam current - 240 atom A, energy of neutrals - 15 keV, magnetic field - 0.2 T, electron temperature 50 eV and target plasma density similar to 10(13)-10(14) cm(-3)) are expected to be sufficient to field reversal in the case, if anomalous ion losses are not essential.

Neutral beam (NB) injector for the TCV tokamak has been designed to produce a deuterium beam with energy 30 keV, equivalent current up to 50 A, and pulse duration 2 s. The injector operation is accompanied by generation of fast neutrons produced in deuterium-deuterium collisions via a nuclear fusion reaction D(D, n)3He. Main sources of the neutrons are a beam neutralizer and a deuterium-saturated surface of beam dump. Measurements of the neutron yields from the both sources were produced on the prototype of TCV injector in the Budker Institute of Nuclear Physics. Neutron yields from neutralizer and beam dump are equal to 9.5x10(8) s(-1) and 2.3x10(9) s(-1) for the nominal parameters of the injector (30 kV, 50 A).