N. P. Sobenin

A dual-energy linac cargo inspection system

X-ray inspection systems for cargo containers, capable of performing Z analysis, are an actively evolving type of equipment for cargo inspections [1–3]. A linear electron accelerator with fast energy tuning, operating in the mode of interlacing low- and high-energy electron pulses, has been developed for use in such a system. The output electron energy in this accelerator can vary in the range of 3–15 MeV under software control. An X-ray radiographic image of a container is obtained in a monoenergetic mode with a beam energy of 9 MeV. Pulses with energies of 4 and 9 MeV are used to recognize materials inside a container (i.e., perform Z analysis). The standing-wave linear electron accelerator operates at a frequency of 2856 MHz, its pulse repetition frequency with different energies is 240 Hz, the pulse duration is 10 μs, and the beam energy in each pulse is >10 J.

Design and tuning of a 40-MeV electron linear accelerator

The 40-MeV electron linear accelerator RELUS-6 with a 100-mA pulse current has been designed. The standing wave accelerator with a biperiodic accelerating structure is composed of four sections and is powered from two 6-MW pulse klystrons. The operating frequency is 2856 MHz. The total length of the accelerating structure is 2.73 m. Calculations have been performed with the aim of selecting the lengths of the first three cells in the first accelerating section and the values of the accelerating field in them, so that the width of the energy spectrum at the end of the accelerator is 2%. The geometry of the accelerating structure and the power input cells has been designed. Four accelerating structures have been manufactured based on the simulation results. The structures have been tuned to the operating frequency, the predetermined accelerating field distribution, and a fixed coupling between the feed waveguide and the accelerating section.

A Multipurpose Pulse Race-Track Microtron with an Energy of 55 MeV

A pulsed 55-MeV race-track microtron that was developed and constructed jointly at the Skobeltsyn Institute of Nuclear Physics, Moscow State University and the Lebedev Physical Institute with the participation of Moscow Engineering Physics Institute is described. The results of calculations of the beam dynamics and the main elements of the accelerator are presented, their design is described, and the results of their measurements and adjustment are presented. The technique and results of the accelerator commissioning are described.

Transverse deflecting structure XFEL TDS INJ

The Transverse Deflecting System XFEL TDS System INJ has been built as the part of the European X-ray Free Electron Laser for longitudinal bunch profile and slice emittance measurements. The 0.7 long Transverse Deflecting Structure (TDS), as the part of the system, has been built on base of the disk-loaded structure with hybrid EH-wave, operating frequency 2997.2 MHz and pulse input RF power up to 3 MW. The structure has been built, tuned and installed in the XFEL Injector beam line. All design parameters have been got at low RF power level. Electron beam has been passed through the whole Injector including TDS.

Components of the radio-frequency system for traveling-wave deflecting structures

Components of a radio-frequency system for deflecting structures of the S-frequency range, which are included in the electron-beam diagnostic complexes for a free-electron laser (XFEL, Germany), were designed. Waveguide-coaxial and waveguide-strip directional couplers, a waveguide absorbing load, a waveguide window, and an E-bend were developed. A connecting element between two deflecting structures in the form of a U-shaped rectangular-waveguide section was also calculated.

Structures with a transverse deflecting field for a free-electron laser

For a system for measuring the length and emittance of an electron bunch in a free-electron laser, the optimal geometry of a structure of the disk-loaded-wa veguide type with a transverse deflecting field at an E11 wave is selected. A well-known configuration of a deflector in the form of a circular diaphragmed waveguide with two holes for stabilizing the plane of wave polarization and two new deflector versions-with an oval shape of the coupling hole and with two grooves in the shell—are considered.

High power RF system for transverse deflecting structure XFEL TDS INJ

The high power RF system (HPRF) is designed for RF feeding of the transverse deflecting structure of the transverse deflecting system XFEL TDS System INJ of the European X-ray Free Electron Laser. The HPRF system includes klystron, waveguide ceramic windows, directional couplers, waveguide vacuum units, spark detector and waveguide line. Operating frequency is 2997.2 MHz. Peak input power is up to 3 MW. The HPRF system has been developed, manufactured and assembled in the XFEL Injector building. The total length of the waveguide line is 55 m from the klystron at the -5 floor to the transverse deflecting structure at the -7 floor. All designed RF parameters have been obtained experimentally at low RF power level.

Measurement of electrodynamics characteristics of higher order modes for harmonic cavity at 2400 MHz

In the frameworks of the High Luminosity Large Hadron Collider (HL-LHC) upgrade program an application of additional superconducting harmonic cavities operating at 800 MHz is currently under discussion. As a possible candidate, an assembly of two cavities with grooved beam pipes connected by a drift tube and housed in a common cryomodule, was proposed. In this article we discuss measurements of loaded Q-factors of higher order modes (HOM) performed on a scaled aluminium single cell cavity prototype with the fundamental frequency of 2400 MHz and on an array of two such cavities connected by a narrow beam pipe. The measurements were performed for the system with and without the matching load in the drift tube..

Investigation of the hybrid electron linac with negative group velocity

Hybrid accelerator, incorporating travelling wave (TW) and standing wave (SW) structures is proposed and discussed. Accelerator can sum up an RF focusing in the SW buncher and lower losses in the TW accelerating structure walls. Moreover, the structure without dumping load is proposed. Input power and beam loading are chosen to minimize power reflection from buncher maintain travelling wave regime in the accelerating structure while beam loading is on. In this case SW buncher operates as a dumping load, so all input power either goes to beam or dissipates in the wall losses, it increases structure efficiency. RF characteristics and beam dynamics simulations have been performed.

Combined generating-accelerating buncher for compact linear accelerators

Described in the previous article [1] method of the power extraction from the modulated electron beam has been applied to the compact standing wave electron linear accelerator feeding system, which doesnt require any connection waveguides between the power source and the accelerator itself [2]. Generating and accelerating bunches meet in the hybrid accelerating cell operating at TM020 mode, thus the accelerating module is placed on the axis of the generating module, which consists from the pulsed high voltage electron sources and electrons dumps. This combination makes the accelerator very compact in size which is very valuable for the modern applications such as portable inspection sources. Simulations and geometry cold tests are presented.