The VEPP-5 injection complex is a source of electron and positron beams for the VEPP-2000 and VEPP-4 complexes and is considered as an injector for the future collider project. The performance of the complex is sufficient for current users, but needs to be improved to serve future setups. Work is underway at the injection complex to improve the stability of operation and ease of use. Current achievements and planned improvements of the injection complex are described.

The parameters of the accelerating structures of linear accelerators have a strong influence on the beam parameters such as the mean energy and the energy spread. One of the most common types the accelerating structures is based on disk loaded waveguides. Imperfections in such structure parameters may be critical for subsequent beam dynamics. We analytically study the influence of the errors of the cell-to-cell phase advance on the beam energy spread and the mean energy on the example of the constant gradient structure. Derived expressions were applied to the case of a large number of accelerating structures, which is relevant for GeV linacs, to obtain accelerated beam parameters in terms of the probabilistic analysis for several values of the injected beam duration.

This work examines some properties of the formation of electron beams for modern SR sources and colliders. Trends in this area are described. Characteristic parameters of such sources for developed and designing accelerator facilities are discussed. Latest developments at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences, in the field of electron guns are described, as well as plans for the development of electron sources at the institute for possible future SR sources and colliders are given.

This paper details the development and testing of the first working prototype of the S-band high-power klystron, accomplished at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences (BINP SB RAS). Upon testing, the klystron demonstrated the following parameters: an operating frequency of 2856 MHz and a peak power output of 50 MW. The paper presents the klystron's design, its constituent units, and pertinent processing procedures, along with discussions on the measurement of its parameters.

The results of analytical estimates of the change in the efficiency of the accelerating structure and the accelerating system as a whole with a shift in the operating frequency of the microwave system of a linear electron accelerator with a traveling wave in the 10-cm range are presented. In order to verify the estimates, the energy characteristics of the electron beam are measured when the frequency of the master oscillator at the microwave power source is changed and the natural frequencies of the SLED system resonators of the LUE-200 accelerator are selected (IREN facility of the Joint Institute for Nuclear Research, Dubna).

A theoretical analysis is made of the formation of longitudinal and transverse emittance of beams of charged particles in photoguns under the influence of repulsive forces of Coulomb fields. In numerical calculations, the characteristics of bunches of charged particles with uniform and Gaussian charge density distributions are compared. The efficiency of the proposed numerical-analytical model is compared with calculations using the Astra program. The obtained numerical and analytical results can be useful in the design of photoinjectors to select the optimal parameters that determine the main characteristics of photoguns.

The first stage of the linear accelerator of the Siberian Circular Photon Source (SKIF) accelerator facility has been successfully commissioned at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences (BINP). This test accelerator facility includes the radiofrequency (RF) gun, magnet system, RF accelerating structures, and diagnostic and control system elements. The aim of the work at the facility is to verify the correctness of solutions chosen for the accelerator design, as well as to get operation experience and to measure the beam parameters that will determine the successful work of the overall SKIF complex. This article describes the main subsystems of the test accelerator facility and briefly presents the first operation results concerning the beam parameters.

The VEPP-5 injection complex is a source of intense electron and positron beams that supplies the VEPP-4M and VEPP-2000 accelerator complexes through the K-500 transport channel. At present, the injection complex is in regular operation. Work is being carried out to improve the performance and stability of the facility, and possible ways of working with perspective beam users are being considered. This article presents a description of the injection complex and the experience of its operation, as well as the latest improvements being considered.

В настоящей работе проведено исследование фазового состава и структуры сплава Ir-16,7 ат. % Ce со стехиометрией CeIr5. Методом рентгенофазного анализа установлено, что сплав не является однофазным, в нем присутствуют в значимых количествах три фазы – CeIr5, Ir и Ce2Ir7. Сплав имеет поликристаллическую структуру, зерна состоят из высокодисперсной эвтектической смеси двух фаз CeIr5+ Ir. Интерметаллид CeIr5 образует матрицу, в которые включены кристаллы Ir. Кристаллы Ir имеют глобулярную и игольчатую форму. Характерный размер глобулярных кристаллов 1-3 мкм, диаметр игольчатых кристаллов 0,5-1,0 мкм. При выходе на поверхность фотокатода иглы Ir образуют столбчатую структуру с радиусом кривизны около 400 нм и плотностью ρ = 33·104 мм-2. Дисперсность структуры обеспечивает большую плотность межфазных границ. Оценка показывает, что на поверхности площадью 1 мм2 длина сети межфазных границ составляет 0,83 м.

The linear accelerator of the Siberian Circular Photon Source is being developed at Budker Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences (BINP SB RAS). The test accelerator facility with the RF gun, the bunching system, the pre-accelerator and the first regular accelerating structuresoperates at Budker Institute of Nuclear Physics. The aim of work at this facility is to demonstrate the performance of the basic system of the linear accelerator, including the accelerating structures. This paper presents the first accelerating structures for the linear accelerator of the SKIF injector produced at BINP SB RAS.

The paper analyzes the results of the first experiments to obtain the design parameters of the RF cannon beam of the linear accelerator of the Siberian Ring Synchrotron Radiation Source (SKIF) and describes the diagnostic methods used in this case. The studied parameters include the transverse and longitudinal profiles of the beam, its emittance, energy and energy spread, current, charge and particle losses. The obtained values are compared with the numerical simulation data.

The new fourth-generation synchrotron light source SKIF is under development in Novosibirsk, Russia. It consists of a 3 GeV electron storage ring with extremely low emittance, a booster synchrotron, and a linear accelerator. The paper discusses essential aspects of the design of the 200 MeV linear accelerator for SKIF, its main characteristics, and parameters in different operation modes. Description of the linac systems is presented.

Photocathodes made of the Ir-Ce system alloys have high thermal resistance, electrical, and thermal conductivity along with high electron emission properties and are widely used as sources of electrons. In this paper, the phase composition and structure of the Ce-83,3ат%Ir alloy intended for use as a photocathode material are studied. The alloy obtained by electron beam melting has a component ratio corresponding to the CeIr5 intermetallic compound. Despite this, a dispersed multiphase material is formed during crystallization. X-ray phase analysis shows the presence of three phases, such as Ir, CeIr5, and Ce2Ir7, in the photocathode material. Optical microscopy studies of the photocathode microstructure reveal that the basis of the alloy is the CeIr5 + Ir eutectic. The CeIr5 phase forms a matrix in which Ir crystals are included. The Ir phase has the form of rods with an average diameter of 0.7 microns. The high dispersion of the structure can increase the emission properties of the photocathode.

The development of the millimeter wavelength structure of cavities is underway at the Budker Institute of Nuclear Physics. The initial interest in such structures is caused by the possibility of obtaining a higher accelerating gradient due to the breakdown limit increase at a higher operating frequency domain. The W‑band structures can also be used for charged particle bunch production for experiments with plasma wakefield acceleration. An analysis of cavity structure excitation by the single bunch was given in our previous studies, as well as a comparison of it with excitation simulations. This paper presents an analysis of the structure excitation by the train of charged particle bunches taking into account the train parameters and the individual detuning of the cavity frequency relative to the bunch repetition rate.

В статье рассмотрен фазовый состав и структура сплава CeIr – эффективного фотокатода с высокой плотностью тока фотоэмиссии, обладающего стойкостью к импульсным нагрузкам лазерного излучения и длительным временем жизни. Фотокатод на основе сплава CeIr предполагается использовать для СВЧ фотопушек как источник электронов перспективных электрон-позитронных коллайдеров с высокой светимостью. На основе анализа фазовой диаграммы системы CeIr установлено, что более устойчивы к повреждениям лазерным облучением и, следовательно, более предпочтительными для изготовления фотокатодов являются соединения Ce–Ir с содержанием Ir более 60 ат.%. Рентгенофазовый анализ показывает, что в сплаве Ce-83%Ir со стехиометрией CeIr5присутствуют в значительных количествах три фазы CeIr5, Ir и Ce2Ir7. Многофазный состав фотокатода объясняется тем, что большинство соединений в системе Ce–Ir кристаллизуются по перитектическим реакциям, что затрудняет получение однофазной структуры. Одним из возможных методов увеличения тока эмиссии является модификация поверхности фотокатода с целью создания высокой плотности активных центров и низкой работой выхода электронов. Модификация поверхности проводилась двумя способами - электролитическим травлением и термической обработкой в вакууме. Это позволяет получить столбчатую структуру поверхности, рельеф которой представляет остроконечные иглы с радиусом закругления 20-30 нм. В результате получен рельеф поверхности фотокатода, способствующий увеличению фактической площади эмиссии электронов.

The Siberian Circular Light Source is a new mediumenergy high brightness synchrotron light facility which is under construction on the Budker Institute of Nuclear Physics (BINP) in Russia, Novosibirsk [1]. The accelerator facility for convenience is divided into three components; a 3 GeV storage ring, a full-energy booster synchrotron and a 200 MeV injector linac with a thermionic gridded RF gun electron source. This paper describes the RF gun design and plans for operation. INTRODUCTION The prototype of the RF gun presented in this paper is the RF gun constructed for Novosibirsk Free Electron Laser facility [2] and the RF gun for VNIIEF [3] that have been extensively tested and operated at BINP and Sarov. The differences are the pulse regime of work instead the continuous one and the higher beam energy (800 keV). It has an oxide thermionic gridded cathode mounted into the RF gun cavity. A trigger pulse with 1 ns width came to the cathode-grid gap at the moment when RF phase voltage in the cavity becomes 40 degrees in order to emit an electron bunch. This bunch is accelerated by the cavity field up to 800 keV. This energy is less than those maximal one that occurred at the launch phase of 70 degrees. So, the 40 degrees bunch has the specific energy distribution of particles that led to bunch longitudinal compress of up to 20 ps at the end of some drift space distance. In order to get the desired 4 ps width bunch, there must be additionally used a special third harmonic cavity. Hereby, the RF gun generates an electron beam suitable for velocity bunching of it down by 250 times on a 3-metrelong drift space containing a third harmonic cavity, a preaccelerator, and a diagnostic and focusing equipment. Respective cavity resonance frequencies are 178, 534 and 2856 MHz. All works in a pulse regime with 1 Hz repetition frequency. There is the possibility to use a higher repetition frequency, e.g., of 20 Hz, to make a conditioning of the cavities. The main requirements to the RF gun are the phase and amplitude field stability of about 1° and 1% respectively. This is followed from the requirement for the electron beam at the linac exit to have no more than 1% of energy spread and energy deviation suitable for injection through the linac-to-buster transfer line into the booster synchrotron. All these cavities together with the linac accelerating structures must be accurate synchronized within 2 psec by the Libera electronic system equipment with master generator frequency of 178 MHz. The temperature of all cavities is stabilized accurate within 0.1 K. Their resonance frequencies, except the pre-accelerator one, are controlled by a precision feedback control system equipped with piezoelectric tuners. Two modes of operation are planed; short-pulse mode, in which a single 1 nC electron bunch is injected into one buster RF bucket and long-pulse mode in which a train of single bunches with the total charge of 16.5 nC is injected into the booster working at an operational frequency of 356 MHz. Such value of charges leads to a beam loading effect those results in voltage drop of cavity acceleration. Simulations show that the maximum voltage drop is less than 1%. Furthermore, a possible phase shift of the voltage due to the sound or thermal impact of the RF power pulse into the cavity is estimated as slow enough to compensate the both by the vector modulator equipped feedback control system. The amplitude and phase of the RF master generator signal is controlled by the vector modulator and drives a solid-state preamplifier. A second 0.7 MW solid state amplifier equipped by built-in circulators, amplifies the signal which is connected to the RF gun by a 6 1/8” coaxial feeder and an RF power coupler. The trigger pulses with 1 ns width and the variable 0÷150 V amplitude are formed by a special transistor scheme displaced into a mobile block inserted into the RF gun and connected to the cathode-grid assembly through a set of collets. The trigger signal is phase controlled by the reference signal of the master generator through electronic equipment made by BINP. The detailed RF parameters of the RF gun are listed in Table 1. The RF gun now is manufactured on the BINP experimental production that will be lasted for 1 year and then will be tested at a special stand-prototype consisting from the third harmonic cavity, pre-accelerator, the first accelerating section of the linac, and the diagnostic equipment in order to test the system during a building structure for the SKIF facility is constructed and made. RF GUN DESIGN The RF gun schematic view is presented in Figs. 1 and 2. ___________________________________________ † v.n.volkov@inp.nsk.su 12th Int. Particle Acc. Conf. IPAC2021, Campinas, SP, Brazil JACoW Publishing ISBN: 978-3-95450-214-1 ISSN: 2673-5490 doi:10.18429/JACoW-IPAC2021-WEPAB149 MC3: Novel Particle Sources and Acceleration Techniques T02 Electron Sources WEPAB149 2965 C on te nt fr om th is w or k m ay be us ed un de rt he te rm s of th e C C B Y 3. 0 lic en ce (© 20 21 ). A ny di st ri bu tio n of th is w or k m us tm ai nt ai n at tr ib ut io n to th e au th or (s ), tit le of th e w or k, pu bl is he r, an d D O I

Hollow Electron Lenses (HEL) will be installed at the High Luminosity Large Hadron Collider to provide a continuous and controlled depletion of beam halo particles by interaction with a superimposed hollow electron beam, of intensity as high as 5 A, and radii 1.1–2.2 mm for 7 TeV LHC operations. In this paper, issues related to the propagation of high intensity hollow electron beams are discussed and the simulations of the electron beam dynamics with feedback to the HEL design are presented. The main results are the rise of the electron beam accelerating voltage from 10 kV, as in the initial proposal, to 15 kV and the validation of the 5 T magnetic field at the main solenoids as being sufficient to guarantee a stable electron beam.

Фотокатоды, изготовленные из сплавов системы Ir-Ce, наряду с высокими электронно-эмиссионными свойствами обладают высокой термической стойкостью, электропроводностью и теплопроводностью и находят широкое применение как источники электронов. В настоящей работе проведеноисследование фазового состава и структуры сплава Ir-16,7 ат.% Ce, предназначенного для использования в качестве материала фотокатода. Сплав, полученный методом электронно-лучевой плавки, имеет соотношение компонентов соответствующее интерметаллиду CeIr5. Несмотря на стехиометрический состав сплава CeIr5, при кристаллизации образовался многофазный материал. Рентгенофазовый анализ показал присутствие в материале фотокатода трех фаз Ir, CeIr5 и Ce2Ir7. Эти фазы имеют высокую температуру плавления относительно других фаз системы Ir-Ce. Исследования микроструктуры фотокатода методом оптической микроскопии, показали, что основой сплава является эвтектика CeIr5 + Ir, по границам которой расположены интерметаллиды Ce2Ir7. Фаза CeIr5кристаллизуется в виде игл со средним диаметром 1,5 мкм. Высокая дисперсность структуры может увеличить эмиссионные свойства фотокатода.

VEPP-5 Injection Complex was designed as a powerful source of intense electron and positron bunches at the energy of 510 MeV. Now Complex is very close to start full scale commissioning. The most important subsystems of Injection Complex (high intensity driving electron linac and positron production system) have been put in operation at designed parameters. The results of positron production system commissioning are presented in this paper.