The project of new accelerator complex NICA relating to nuclear and hadron physics require a more powerful longitudinal and transverse cooling that stimulates searching new technical solutions. The new accelerator complex NICA is designed at the Joint Institute for Nuclear Research (JINR, Dubna, Russia) to do experiment with ionion and ion-proton collision in the energy range 1-4.5 GeV/u for studying the properties of dense baryonic matter at extreme values of temperature and density with planned luminosity 1027 cm-2s-1. This value can be obtained with help of very short bunches with small transverse size. This beam quality can be realized with help of stochastic and electron cooling at energy of the physics experiment. The electron cooling system on 2.5 MeV consists of two coolers, which cool both ion beams simultaneously. The Budker Institute of Nuclear Physics (BINP SB RAS) has already built and commissioned the electron cooling system for the NICA booster, and now it develops the high voltage electron cooling system for the collider. The article describes the construction and status of the cooler development.

The presented report contains the description of highvoltage source with output voltage up to 300 kV and output current up to 50 mA. The source consist of the chopper with IGBT switches working with a principle of pulse-width modulation and the full H-bridge converter with IGBT switches, both working on programmed from 15 to 25 kHz frequency, and the high voltage transformer powering the eight-stage multiplier with the additional capacity filter at output. The transformer and multiplier both are made in common volume separated on oil tank part with silicon oil for transformer and SF6 part for multiplier. The additional capacity filter provides low ripple and noise level in working range of output currents. The source can operate in normal mode with series of high-voltage breakdown in output voltage. In the highvoltage breakdown the released in load and matching circuit energy is less than 40 J at maximum operating voltage 300 kV. The efficiency of system is more than 80% at the nominally output power 15 kW. The description of the source and the test results are presented. DESCRIPTION The presented source was designed for accelerator electron gun of Siberian Synchrotron and Terahertz Radiation Centre. That was reason for some specific terms like: strong reliability to high-voltage breakdown, low energy dissipated in high voltage breakdown, low voltage ripple for maximal power operation. The energy is dissipated in components of source and in the load during the high voltage breakdown less than 30 J for 260 kV operations. The basic characteristics of high-voltage source are shown in Table 1. OVERVIEW The circuit diagram of power part of high-voltage source is shown in Fig.1. The high-voltage source consists of the 20 kHz power converter with insulated gate bipolar transistors (IGBT) as switches (part A) and high-voltage transformer with the four-stage multiplier (part B). The power converter consists of 3-phase rectifier VD1, electromagnetic (EMI) filter F1, switch SW1, rectifier’s filter capacitors C1-C2, 20 kHz chopper with IGBT switch Q1, 20 kHz inverter with IGBT switches Q3-Q6, output filter circuit L2 C5 C6, and isolation transformer T1. Input Rectifier EMI filter is used to eliminate high-frequency noise to the power line from the source. 3-phase rectifier and filter C1-C2 is used to convert input AC 3-phase voltage 380 V 50 Hz to DC-link 550-600 V voltage. Contactor SW1 consists of 2 groups of contact: the first is used for soft start of converter and another is used for normal operations. Table 1. Basic Characteristics of High-Voltage Source Parameter Unit Min Nom Max Output voltage kV 10 260 300 Output current mA 15 50 Output power kW 15 Voltage ripple (full load) % 0.2 Long term stability % 0.1 Transient time ms 50 Converter frequency kHz 15 20 25 Chopper The chopper switch Q1 is operated with principle of pulse-width modulation on programmed from 15 kHz to 25 kHz frequency synchronously with inverter. The output voltage of chopper is changed from 10 to 450 volts DC by control circuit to obtain the required output high voltage of source. Inverter Full-bridge inverter Q3-Q6 converts DC voltage from chopper’s capacitors C3-C4 to AC voltage with programmed from 15 to 25 kHz frequency. Filter Circuit The matching circuit consists of elements C5 and L2 and low pass filter L2 C6 are used for minimizing transient process and for improving efficiently of design. The matching circuit is used for protection reasons. When there is a high voltage breakdown or over current the matching circuit limits the rate of current rise in the inverter. Magnetising inductance of high voltage transformer, its capacitance calculated to primary side in parallel with C6 and the matching circuit organize lowpass filter for all high harmonics of inverters rectangular waveform voltage. That way, sinusoidal voltage is feed in the high-voltage transformer, because all high harmonics are filtered. In other case, the presence of high harmonics causes power dissipation in the coils because of skineffect. Also this harmonics can induce the singing in the winding of high-voltage transformer and this effect increases the output zero load voltage and complicates the reduction transient over voltage. THPSC029 Proceedings of RuPAC2016, St. Petersburg, Russia ISBN 978-3-95450-181-6 606 C op yr ig ht © 20 17 C C -B Y3. 0 an d by th e re sp ec tiv e au th or s Magnetic and vacuum systems, power supplies

A high efficiency electron collector for the COSY high voltage electron cooling system was developed. The main feature of the collector is usage of special insertion (Wien filter) before the main collector, which deflects secondary electron flux to special secondary collector, preventing them fly to the electrostatic tube. In first tests of the collector in COSY cooler efficiency of recuperation better then 10⁻⁵ was reached. Before assembling of the cooler in Julich upgrades of the collector and electron gun were made. After the upgrade efficiency better then 10-6 was reached. Design and testing results of the collector are described.

There are the structure and control algorithms 10kW power source with 25 kHz converter and output synchronous rectifier shown in the article. The output voltage or current of power source has controlled waveform with 1 kHz maximal frequency. The output voltage is galvanically isolated from mains. The source design allows using the load’s energy recuperation in the power converter storage capacitor and soft switching in the synchronous rectifier. The article shows the application of power source as 400 Hz waveform regulated sinusoidal voltage generator.

A. Zhuravlev, A. Batrakov, A. Chernyakin, V. Kiselev, V. Konstantinov, A. Pavlenko, V. Petrov, E. Semenov, D. Senkov, BINP, Novosibirsk, 630090, Russia Abstract Magnets for injection and extraction sections of NSLS-II 3 GeV booster are designed, manufactured and tested at BINP, Russia. This report considers the details of bump and septum magnets design, their parameters and results of the inspection test at BINP. The design and electronics features of the measurement stand for these magnets are presented. Also, capabilities of specialized power supplies are listed and discussed.

Budker Institute has designed and delivered Booster for NSLSII project including vacuum system, magnet system, diagnostics and power supplies. Dipole power supplies were directly delivered to BNL by sub-contractor (Danfysik, Denmark). To test dipole magnets on factory side, at BINP, it was decided to design and construct a high current ramping mode power supply. The designed power supply can operate with the reactive output power up to 150kVA and output current up to 900A at 2Hz ramping mode. The absolute accuracy achieved is better than 100ppm for the injection and extraction flats and better than 500ppm for the ramps. PARAMETERS

The 2 MeV electron cooler for the COSY storage ring (FZJ) is being assembled at BINP. The electrostatic accelerating column generates a high-energy electron beam. The power supply for the accelerating column of the electron cooling system consists of 33 controlled modules distributed by the accelerating potential. Each module has a precision controlled voltage source for 60 kV, 1mA and an additional supply for the solenoids of the magnetic system with a maximum current of 2.5 A. All the systems are controlled through the wireless ZIGBEE network. This report presents the structure of the power system, its parameters, and the results of tests carried out at BINP.

Power system for quadrupole magnets of NSLS-II 3 GeV booster designed, manufactured and tested in BINP, Russia. The power system consists of 2 parts. First part is charging source with capacitance bank at output. And the second part is 3 current sources powered by a capacitance bank. The charging source output voltage is up to 180 V, peak power is 40 kW and average power is 20 kW. Capacitance bank has 120 kVA storage energy. Second part contains 3 independent current sources with up to 180 A output current each. This report considers the details of current sources design, their parameters and results of inspection test in BINP. Finally, the first results of injection and extraction section commissioning at BNL site are reported. INTRODUCTION The presented current source was designed for supply of quadrupole magnets of NSLSII booster. The parameters of quadrupole magnets power system are shown in Table1. There are three group of quadrupole magnets is used BF BD BG. Those way three current sources are needed. Current scenario for quadrupole magnets is shown in Fig.1. In the beginning there is an injection plateau the current should be about 1/15 from the maximum current and have the stability not worse than 0.01 %. It is followed by a controllable rise of current. The current stabilization accuracy at rising should be better than 0.1 %. Then there is a flat-top for extraction of the particles with the fixed energy – followed by fall. The repetition period is 1 Hz. Table 1: Quadrupole Magnets Power System Parameters Figure 1: Current scenario. DESCRIPTION Overview The load parameters are the same for each channel. Load inductance is 0.14 Hn. Load resistance is 0.3 Om. At the specified current scenario, the average power of active losses is 2.5 kW for channel, the energy accumulated in inductance is 2 kJ. Time constant of the magnets is approximately 0.5 sec, thus, to provide the current fall during the necessary (<0.2 sec) time, the current source should be two-quadrant and the part of current from inductance at fall should be recuperated to the source buffer capacitor. The capacitance value is 0.1 F per channel for 40 V over voltage and 200 V operating voltage. The selected diagram of power source is shown on Fig.2. The common 30 kW bulk power supply with 200 V output voltage and common 0.3 mF capacitance bank are used. Three separate current sources are powered from capacitance bank. Each of the Output sources has their own channel of computer control via PSC and PSI controllers. Bulk Power supply is controlled current sources by local bus. The circuit with the single bulk PS and the common capacitance allows optimizing the magnet energy recuperation for asynchronous operation or for different values of maximum currents in channels. Figure 2: Power system block diagram. Parameter QF QD QG Lenses per channel 8QF 8QD 8QG Current, A 167 118.3 105.3 Resistance per string, Ω 60

The electron cooler of a 2 MEV for COSY storage ring FZJ is assembled in BINP [1]. Results of experiments with high voltage, with electron beam, cascade transformer for distribution power along acceleration tube will be discussed in this report. The COSY cooler is designed on the classic scheme of low energy coolers like cooler CSRm, CSRe, LEIR that was produced in BINP before. The electron beam is transported inside the longitudinal magnetic field along whole trajectory from an electron gun to a collector. This optic scheme is stimulated by the wide range of the working energies 0.025÷2 MeV. The electrostatic accelerator consists of 33 individual unify section. Each section contains two HV power supply (plus/minus 30 kV) and power supply of the magnetic coils. The electrical power to each section is provided by the cascade transformer. The cascade transformer is the set of the transformers connected in series with isolating winding.

Pulse generators for injection and extraction systems of NSLS-II 3 GeV booster designed, manufactured and tested in BINP, Russia and installed and tested at BNL site. This report considers the details of bump injection septum and extraction septum pulse generators design, their parameters and results of inspection test in BINP. The design and electronics features control system of pulse generators are presented. Finally, the first results of injection and extraction section commissioning at BNL site are reported. INTRODUCTION NSLS-II is a new third-generation storage-ring light source that is under construction at Brookhaven National Laboratory. The booster NSLS-II will accelerate electrons from 200 MeV to the nominal energy of 3 GeV. The repetition rate of the booster is 1 or 2 Hz, depending on the state of the injector. In order to reduce the requirement for the linac’s beam charge, the booster injection was designed to provide beam stacking with 100 ms stacking time [1][2]. Pulsed magnets are used for the beam injection and extraction to the booster. Table 1 shows the parameters of the power systems for septums and bumps magnets. Table 1: Pulsed Magnet Power System Parameters Parameter Injection septum Extraction septum Bump magnets Energy, MeV 200 3000 3000 Field, T 0.111 0.8 0.46 Self-inductance, μH 1.8 2.1 55 Bank capacitance, μF 60