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The work is dedicated to one of the systems of the NESTOR X-ray generator. The injection system is at the highest stage of readiness after the magnetic system. Structurally, the injection system can be represented as an injector (linear accelerator), channel of parallel transportation (transport channel), channel of the beam entry into the vacuum chamber, and pulsed inflector. All equipment has been tested, and the beam passed through all the components in the volume of the storage ring.

We designed a 100 MeV/100 kW electron linear accelerator for NSC KIPT, which will be used to drive a neutron source on the basis of subcritical assembly. Beam dynamics studies have been conducted to reach the design requirements (E=100 MeV, P =100 kW, dE/E

The possibility of efficient bunch compression due to the phase motion of particles in the field of a traveling wave is demonstrated. The calculated bunch length is 120 μm, which makes it possible to expect spontaneous coherent radiation from the undulator at a wavelength of 240 μm.

The report presents design and simulated performances of the S-band electron bunching system based on coupled cavity chain in which the on-axis field amplitude changing substantially from the cell to the cell. For realization of such field distribution the operating frequency of the bunching system, which is close to the eigen frequency of the last cell, is higher than frequency of the "/spl pi/" mode of the rest part of the bunching system. Cell lengths are chosen in the way to get the effective bunching and accelerating of the beam from the initial energy of 25 keV to the energy about 1 MeV with the current of 300 mA. The bunching system can be used in electron linacs both for fundamental researches and for radiation technologies.

The investigation of beam generation in magnetron guns with small anode-cathode gap has been carried out. The main attention was paid to study of an initial stage of space charge arising and providing steady-state regime of secondary emission multiplication.

The problem of extending the life-time, of increasing the pulse and average power of many RF-sources is closely related to the design of their electron guns. As it is known, the magnetron injecting guns with secondary emission metallic cathodes (SEMI) are specified by the high current emission density and long life-time. The main goal of these investigations is to determine the advantages and limitations of using SEMIGs as the electron source in high-power RF devices and accelerator injector systems. At this stage we have studied some questions concerning the operational beam stability, voltage and current increasing. The experiments have been performed by using the experimental setup to investigate SEMIG linear electron beam parameters from single and multiple beams gun assemblies with the anode voltage up to 100 kV, pulse duration up to 10 /spl mu/s, repetition rate 50 Hz and 0.1-0.2 T magnetic field strength. Pulse-to-pulse long-term stability of the annular electron beams (internal diameter nearly equal to the cathode diameter, wide of ring 1-2 mm (wavelength of cyclotron oscillations)) with beam density up to 70 A/cm/sup 2/ (10/sup 10/-10/sup 11/ e/sup -//cm/sup 3/) have been achieved. It is shown, that the cathode diameter extension provides a proportionate increasing of the beam current, and in the case of multiple beam gun assemblies we have separate identical electron beams with the similar parameters of single-beam gun.

The results of design and research of S-band radio frequency electron guns (RF guns) with different cathode types are presented.

Kharkov Institute of Physics and Technology (KFTI) has designed and constructed a linear resonance electron linac (LREA) with an average beam power up to 12 kW and beam energy of 8–10 MeV. The accelerator pilot test was made in September 1393. To manage operation of the accelerator a control system has been developed, providing for beam current and energy monitoring, control over systems parameters and failure diagnostics. It provides cross-correlation signal analysis, accelerator guide protection from beam loss and radiation hazards, modulator and klystron amplifier lockup protection against incorrect operation, current adjustment in the lattice power supplies, and control of RF-signal phase-power characteristics in the injection unit.

The paper presents calculated performances and the electron linac arrangement that is under installation at NSC KIPT. The linac consists of two 1.2-meter long piece-wise homogeneous accelerating structures and the injector including a diode electron gun, a klystron type buncher and an accelerating cavity. The wave phase velocity in the structures is equal to the velocity of the light. Each accelerating structure is powered with the Russian produced S-band klystron KIU-12AM. The linac is equipped with the beam scanning system to extract the beam through an air-cooled foil. The simulation of electron motion in the accelerator was carried out using the PARMELA code. When each accelerating structure is supplied with RF power of 11 MW, and the current at the accelerator exit is 1 A, the beam energy will be up to 20 MeV. An average beam power is planned to be 20 kW.

Analytical and numerical investigations of the trajectories of probing beam electrons in a two dimensional wake-field, generated in a plasma by a dense bunch of relativistic electrons with Gaussian longitudinal and transverse distributions of density have been carried out. Based on the calculations of probing beam deviations, the diagnostic instruments are developed for the parameters of experiments conducted at NSC KIPT. The diagnostic instruments include an electron gun generating a 10 keV electron beam with a current of 10 /spl mu/A and 2 mm in diameter, which passes through the chamber of interaction and falls on the collector of 10 mm diameter. The collector (screen) is placed in front of the first plate of a microchannel amplifier which consists of three microchannel plates (MCP) with sizes between 20 and 30 mm. The 3 kV voltage was applied to each plate. The total amplification of MCP amplifier is 10/sup 4/ to 10/sup 5/ depending on the number of particles incident on the first plate. As a result of probing beam deviations due to the excited wake-field, the electrons fall on the first plate of the amplifier and are registered by its anode located behind the third plate. The calculated probing beam deviations and the amplification attained with the MCP amplifier permit one to detect and investigate the electrical wake-fields excited by a sequence of relativistic bunches ( number of particles in a bunch is 2/spl middot/10/sup 9/, energy is 14 MeV) in a plasma of 10/sup 11/-10/sup 13/ cm/sup -3/ density. The intensity of the fields registered by this technique is no less than 2 kV/cm.

The investigation into the generation of tubular electron beams and their parameters in a system of secondaryemission cathodes was carried out. The parameters of electron beams in a multi-cathode secondary-emission source and a single magnetron gun with the use of a multi-channel measuring system were measured. The stability of the beam current amplitude and a net charge in the beam (pulse to pulse), current distribution on the azimuth were studied. In the 8-cathode system at a cathode voltage of ~34 kV and a magnetic field strength of ~3500 Oe the total current of all beams was ~35 A and its stability was 4÷5%. In the single magnetron gun at a cathode voltage of ~30 kV and a magnetic field strength of ~2500 Oe the beam current was ~60 A. And its stability was 2÷4%.

The RF gun operation with metal-dielectric cathode is reviewed in the paper. The beam is extracted from the plasma developed during the microwave flashover dielectric in vacuum. The cathode was designed and electron beam dynamics was computer simulated. Modes of the gun operation were researched experimentally on the linear resonance electron accelerator. The beam at the gun output has the pulse current of 3.5-4.5 A with the current pulse duration of 40-50 ns and with particle energy of 300 keV. Some treatments of the beam development and the gun cavity response to the flashover in high intensity RF fields are given.

Results are presented of experimental studies on beam parameters at the exit from an RF-injector and a single-section accelerator. It is demonstrated that owing to an assigned amplitude and electromagnetic field phase relationship in the RF-gun during the pulse, one can get in a position to optimize bunches inflight phases into the accelerating section during which compensation is observable of the beam energy spread induced by current loading of accelerating section.