Oleg Meshkov

Picosecond streak-cameras for bunch diagnostics in accelerators

Temporal parameters of synchrotron pulse radiation at damping ring (DP) installation of VEPP-5 type were measured with the help of PS-1/S1 picosecond streak camera having 1.5 ps time resolution. These measurements were proceeded within 400-900 nm spectral range. It has been shown that our streak camera may record either a train of electron bunches with ns-duration or internal structure inside a single bunch. We were able to record the distance ~ 1.5 ns between separate bunches as well as their amplitude, which depends on particle numbers inside a bunch. Depending on linear accelerator mode of operation it was possible to define a single bunch duration, which was deviated within the range of 20-100 ps. The temporal structure of a single bunch was measured with 1.5 ps time accuracy. As a result, the VEPP-5 damping ring parameters were optimized, and particles injection conditions were improved. In addition, we have measured the temporal parameters of Vavilov-Cherenkov radiation (VCR) emitted by electron beam of linear accelerator. Our results provided important information on electron bunches formation and their quality inside linear accelerator before electrons injection inside a damping ring. Another series of experiments were done at VEPP-4M electron-positron collider. The dependence of beam length of the beam current measured with streak-camera allowed us to compute the wide-band impedance of the accelerator. The same data were obtained at Siberia-2 synchrotron radiation source (NRC “Kurchatov Institute”, Moscow).

Development, calibration and application of new generation dissector with picosecond temporal resolution

A dissector is an electron-optical device designed for measurement of periodic light pulses of subnanosecond and picosecond duration. LI-602 dissector developed at Budker Institute of Nuclear Physics (BINP SB RAS) is widely used for routine measurements of a longitudinal profile of electron and positron beams at BINP electron-positron colliders and other similar installations(1,2). LI-602 dissector is a part of many optical diagnostic systems and provides temporal resolution of about 20 ps. Recently a new generation of picosecond dissectors were created on the basis of the PIF- 01/S1 picosecond streak-image tube designed and manufactured at the A.M.Prokhorov General Physics Institute (GPI) Photoelectronics Department(3,4). The results of the measurements of instrument function of the new dissector based on PIF-01/S1, which were carried out in the static mode(5) showed that temporal resolution of the dissector can be better than 3-4 ps (FWHM). The results of temporal resolution calibration of the new-generation picosecond dissector carried out at the specialized set-up based on a femtosecond Ti:sapphire laser and recent results of longitudinal beam profile measurements at BINP damping ring are given in this work.

An Experimental Study of Beam Dynamics in the ERL-Based Novosibirsk Free Electron Laser

Transverse and longitudinal dynamics of the electron beam of the Novosibirsk infrared Free Electron Laser is studied. The Novosibirsk FEL is based on the multi-turn energy recovery linac (ERL). The ERL operate in CW mode with an average current about 10 mA. Therefore non-destructive beam diagnostics is preferable. The beam energy at the last track of the ERL is 42 MeV. As a result, significant part of synchrotron radiation from bending magnets is in the visible range. The transverse beam dimensions were measured with the optical diagnostics before and after the undulator applied for generation of middle-infrared coherent radiation. The obtained data is used to calculate the beam energy spread and emittance. The longitudinal beam dynamics was studied with electro-optical dissector. INTRODUCTION The Novosibirsk FEL facility [1] includes three FELs. All the FELs use the electron beam of the same multi-turn energy recovery linac. Scheme of Novosibirsk FEL is shown in Fig. 1. The third FEL is installed on fourth track which is the last one and electron energy here is 42 MeV. Beam from the injector is accelerated four times before it is used in the undulator of the third FEL. The used beam is decelerated four times in the same RF structure and absorbed in the beam dump. Figure 1: The Novosibirsk FEL. The first lasing of the third FEL was obtained in summer 2015. The designed power is 1 kilowatt at repetition rate 3.75 MHz EXPERIMENTAL SETUP Synchrotron Spectrum The Novosibirsk FEL applies the energy recovery technology. The beam energy in the third stage of NovoFEL is 42 MeV. It allows us to use a synchrotron radiation from the bending magnets for optical diagnostics of the parameters of the beam. The bending radius in magnets before and after the fourth track is 0.655m. The calculated spectrum of synchrotron radiation is presented in Fig. 2. Figure 2: Synchrotron radiation from the bending magnet of the third FEL. Critical wavelength of the spectrum is 5016 nm. There are enough photons in optical wavelength range to acquire the synchrotron radiation and measure the bunch parameters. Technical Limitations There are two main problems with the design of optical diagnostic systems. Synchrotron radiation of the beam has a divergence about 10-2 rad and it is difficult to deliver it out of the experimental hall without significant intensity loss. Another problem is a high residual activity created by the beam after half–hour operation of the third stage of NovoFEL. Considering these restrictions, diagnostics tools have to be installed as close as possible to the optical output of the bending magnet and a remote control of optics must be implemented. Transverse Sizes Measurement Radiation hardened CID camera is used to acquire transverse beam profile (Fig. 3) [2]. The camera receives the synchrotron radiation from the bending magnet placed after the undulator. Proceedings of IPAC2017, Copenhagen, Denmark THPAB036 05 Beam Dynamics and Electromagnetic Fields D09 Emittance Manipulation, Bunch Compression and Cooling ISBN 978-3-95450-182-3 3781 Co py rig ht

Longitudinal Beam Distribution Measurements in Damping Ring of VEPP-5 Injection Complex

Injection Complex VEPP-5 was turned into operation in the end of 2015 in the Budker Institute of Nuclear Physics (Novosibirsk, Russia). The main task of the facility is production, acceleration and transportation of high intensity electron and positron beams for two BINPs colliders. Now, VEPP-5 successfully delivers electron and positron beams to the collider VEPP-2000 and ready to start operation with the acceleration complex VEPP-4M. Beam diagnostics issues are very important for VEPP-5 facility tuning during the operation. Longitudinal beam diagnostic based on synchrotron radiation in the VEPP-5 Damping Ring is presented in the article. Equipment operation principle, main measurement results and future prospects are presented in this paper.

A high-speed electron beam profile monitor for the synchrotron radiation source

The real-time processing of the electron beam parameters is a necessary procedure to optimize the key characteristics of the synchrotron radiation source. To study multi-bunch beam instabilities a high-speed electron beam profile monitor is developed. The device described must continuously implement 15625000 measurements of the vertical or horizontal electron beam profile at 16 points with a time resolution of 5 ns at 50 MHz rate.

New station for optical observation of electron beam parameters at electron storage ring Siberia-2

The paper is dedicated to a new station for optical observation of electron beam parameters which was built at the synchrotron radiation (SR) storage ring SIBERIA-2 at Kurchatov Institute. The station serves for the automatic measurement of electron bunches transverse and longitudinal sizes with the use of SR visible spectrum in one-bunch and multi-bunch modes.