RuPAC-2010 - List of Keywords (cathode)

A B C D E F G H I K L M O P Q R S T U V W

cathode

Paper	Title	Other Keywords	Page
TUCHC01	Concepts for Rasing RF Breakdown Threshold by Using Multi-Moded Cavities	acceleration, electron, coupling, radiation	24
	S. V. Kuzikov IAP/RAS, Nizhny Novgorod J. L. Hirshfield Yale University, Physics Department, New Haven, CT Y. Jiang Yale University, Beam Physics Laboratory, New Haven, Connecticut S. Kazakov, M. E. Plotkin, A. A. Vikharev Omega-P, Inc., New Haven, Connecticut
	Funding: Work sponsored by in part by US Department of Energy, Office of High Energy Physics (2009). Two multi-mode cavity designs aimed at increasing accelerating gradient are developed. The cavity of the first type has circular cross-section but allows excitation of several equidistantly-spaced eigenmodes by a bunched drive beam. This multi-mode excitation allows to reduce exposure time of the cavity surface by high field, which in this case occupies smaller area. This feature promises to provide more than 30% raise of the threshold in a 3-mode cavity. The second cavity type is axisymmetric but longitudinally asymmetric, and is excited in one mode at the fundamental frequency and the other at the second harmonic. Superposition of these modes always produces a low field on one cavity wall and a high field on the other, with the latter directed so as to prevent electron emission. This feature is also expected to raise the breakdown threshold. Computations show that a structure using such cavities might support an accelerating gradient up to 47% greater than that for a structure using similar single-mode cavities.
	Slides

TUPSA010	Attosecond and Femtosecond Electron Bunches Obtainable Upon Field Emission in a Combined Quasi-static and Laser Electric Field	electron, laser, radiation, bunching	56
	V. A. Papadichev LPI, Moscow
	Short pulses of electrons of femtosecond and attosecond duration are necessary for numerous applications: studying fast processes in physics, chemistry, biology and medicine. It was shown that it is possible to generate electron bunches due to field emission of T/2 - T/8 duration (T is the period of laser oscillation), i.e., 400 as to 20 fs with neodymium or carbon dioxide lasers. Currents of 10 mA to 10 A can be obtained from single-spike cathode and up to 10 kA with a multi-spike cathode. Further bunching occurs due to velocity modulation in the bunch by laser electric field resulting in 6 as for neodymium laser and 120 as for carbon dioxide laser*. Transverse focusing of such bunches is discussed. Heating of spikes for single-pulse regime is several degrees and therefore it is possible to generate a sequence of electron bunches (up to 100 – 500 pulses). They can be used in diffractometry and after acceleration to 3 – 4 MeV for generation of short pulses of VUV and soft X-ray radiation in periodic fields or as a relativistic mirror. Influence of space-charge force are studied using simple analytical solutions and methods to compensate it are proposed. P. Emma. Proc. EPAC04, p. 225, Lucerne, Suisse. V. A.Papadichev. Proc. EPAC08, p. 2812, Genoa, Italy. * V. A.Papadichev. Proc. EPAC08, p. 2815, Genoa, Italy.

TUPSA011	Hollow Photocathode Concept for E-gun	laser, electron, emittance, vacuum	59
	M. A. Nozdrin, N. Balalykin, V. Minashkin, G. Shirkov, E. Syresin, G. V. Trubnikov JINR, Dubna, Moscow Region J. Huran Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava
	Photocathodes are the key devices for high-quality electron bunches generation. Such bunches are needed as initial electron source in contemporary linear accelerators. In all cases there are several important parameters: fast response time, quantum efficiency, long lifetime, low thermal emittance, minimal effect on RF properties of the accelerating system. In this paper the new concept of the photocathode is proposed – hollow (absolutely transparent for the laser beam) photocathode. Such cathode geometry allows quantum efficiency rising due to surface photoelectric effect which is concerned with normal to material surface wave electric field multiplier. Usability investigation experimental results for both hollow photocathodes made of bulk materials (Nb, Cu) and by thin-film technology (CsITe and diamond-like carbon as film on copper substrate) are given. After Nb hollow photocathode irradiation by a laser beam (Lambda = 266 nm, tau pulse = 15 ns, frequency 1 Hz) a charge of 64nC was extracted. Backside irradiation radically simplifies laser beam targeting on emitting surface, accelerator equipment adjustment and allows photocathode working surface laser cleaning.

TUPSA039	HV Electron Cooler for the NICA Collider	electron, acceleration, gun, collider	125
	I. N. Meshkov, E. V. Ahmanova, A. G. Kobets, R. Pivin, A. Yu. Rudakov, A. V. Smirnov, N. D. Topilin, Yu. A. Tumanova, S. Yakovenko JINR, Dubna, Moscow Region A. A. Filippov Allrussian Electrotechnical Institute, Moskow A. V. Philippov, A. V. Shabunov JINR/VBLHEP, Dubna, Moscow region
	The goal of the cooling system of the NICA collider is to meet the required parameters of ion beams in energy range of 1 - 4.5GeV/u that corresponds to the 0.5 - 2.5 MeV of the electron energy. The electron cooler project is developed according to the world experience of similar systems consruction. The main peculiarity of the electron cooler for the NICA collider is use of two cooling electron beams (one electron beam per each ring of the collider) that never has been done before. The acceleration and deceleration of the electron beams is produced by common high-voltage generator. The cooler consists of three tanks. Two of them contain acceleration/deceleration tubes and are immersed in superconducting solenoids. The third one contains HV generator. The scheme of the electron cooler, its main parameters and operation regime are presented.

WEPSB029	Electron Gun and Collector for 2 Mev Electron Cooler for COSY	electron, gun, vacuum, controls	233
	A. V. Ivanov, M. I. Bryzgunov, A. V. Bubley, V. M. Panasyuk, V. V. Parkhomchuk, V. B. Reva BINP SB RAS, Novosibirsk
	COSY storage ring will be upgraded in 2011 by installation of a new electron cooler. Electron cooling will reduce energy spread of protons and so improve the precision of internal target experiments. Some of the most important parts of this new electron cooler are the electron gun and the collector, and they must satisfy several rigid requirements. Electron gun must provide high perveance electron beam with low transversal temperature and variable beam profile. The gun control electrode assembled of four separate sections will provide measurements of beam envelope along the transport section of the cooler. Displacement of corresponding part of the beam may be observed if alternating voltage is applied to each section. Collector should have high perveance, low secondary emission coefficient, and small dimensions. Wien filter is supposed to be installed before the collector to satisfy these requirements. In this case we can use high perveance small-scale collector with axially-symmetric magnetic field; secondary electrons will be absorbed in Wien filter. An additional vacuum pumping must be provided in the collector design.

WEPSB036	Experience on Operating High-Voltage Accelerators Designed in NIIEFA on Industrial Facilities Intended for Polymer Materials' Modification	electron, radiation, extraction, shielding	251
	V. P. Ovchinnikov, V. P. Maznev, M. P. Svinin NIIEFA, St. Petersburg V. I. Alexandrov Izhevsk Plastics Plant JSC, Izhevsk E. M. Kolchin Insulating Polymer Materials, Ltd, Saint Petersburg
	High-voltage accelerators "Aurora-5" and "Electron-10" designed and manufactured in the D. V. Efremov Institute have been operated at the plastic-production plant in Izhevsk and the joint-stock company "Terma", St. Petersburg on facilities intended for production of polymer materials with specific properties due to radiation processing. The results of accelerators’ operation are considered in the paper. The annual operating time of each facility is 5-7 thousand hours, which meets the requirements for industrial equipment.

THPSC011	Investigation on the Electron Beam Formation in the Magnetron Gun with a Secondary-Emission Cathode Using the Masgnetic System Based on Permanent Magnets	electron, gun, permanent-magnet, vacuum	349
	N. G. Reshetnyak, M. I. Ayzatskiy, V. N. Boriskin, I. A. Chertishchev, A. N. Dovbnya, N. A. Dovbnya, V. P. Romas'ko, V. Zakutin NSC/KIPT, Kharkov
	The paper presents the results of investigations on the electron beam formation in the magnetron guns with secondary-emission cathodes using the magnetic system based on annular permanent magnets. The magnetic system, made of NdFeB material, has 10 cm in length, external diameter of 80 mm, internal diameter of 60 mm and longitudinal magnetic field amplitude of 800 Oe. Experiments were carried out using the magnetron guns having cathodes with diameters from 6mm to 16 mm, 75 mm in length, and an anode of 56 mm in diameter. The cathode voltage was 15…25 kV. The experimental results have demonstrated that the magnetron guns with cathodes having 6mm, 10mm and 16 mm in diameter can form tubular electron beams. Under the cathode voltage of 18 kV the electron beam current is ~3.5…5 А. The beam current dependence on the voltage obeys to the "3/2" law. As the cathode voltage was increased to 22 kV, the beam current bunch generation and anode current of ~1.0 mks were observed. As a result of investigations a compact magnetron gun with a secondary-emission cathode and a magnetic system on the base of annular permanent magnets was constructed.

THPSC017	High-voltage Source with Output Voltage up to 60kV with Output Current up to 1A	controls, feedback, impedance, power-supply	357
	D. V. Senkov, I. A. Gusev, A. S. Medvedko, A. Yu. Protopopov, D. N. Pureskin BINP SB RAS, Novosibirsk
	The presented report contains the description of high-voltage source with output voltage up to 60kV and output current up to 1A. The source consist of the chopper with IGBT switches working with a principle of pulse-width modulation and the H-bridge converter with IGBT switches, both working on programmed from 15 to 25 kHz frequency, and the high voltage sectioned transformer with the rectifier and additional capacity filter. The transformer is made in oil tank with silicon oil. The additional capacity filter provides low ripple and noise level in working range of output currents. A nominal output voltage of the source is 60kV, maximal voltage is 80kV. The source can operate in normal mode with series of high-voltage breakdown in output voltage. In the high-voltage breakdown the released in load and matching circuit energy is less than 15 J at maximum operating voltage 65kV. The efficiency of system is more than 80% at the nominally output power 60kW. The controller of the source is developed with DSP and PLM, which allows optimizing operations of the source. For control of the source serial CAN-interface is used. The description of the source and the test results are presented.

THPSC021	Improving of the INR DTL Tank Accelerating Voltage Stability by Means of the Anode Modulator Feedback	feedback, controls, vacuum, pick-up	366
	A. I. Kvasha RAS/INR, Moscow
	The INR DTL RF system consists of five RF channels with output pulse RF power from 1 to 2.5 MW. In turn, in every channel there are four RF vacuum tube amplifiers and two anode modulators. The output RF power amplifier anode modulator with hard discharger (vacuum tube GMI-44A) is used as executive device of accelerating voltage control system. The pulse transformer data at the GMI-44A input and time delay in the feedback of the control system don't allow ensuring the required accelerating voltage stabilization. Improving in a few times of accelerating field stabilization can be achieved by means of anode modulator feedback. Results of a numerical simulation of both feedbacks using MicroCap 8 are presented.

THPSC031	The Use of the Electron Beam from the Magnetron Gun-Based Accelerator for Zirconium Surface Modification	electron, gun, target, vacuum	384
	V. Zakutin, A. N. Aksyonova, A. N. Dovbnya, S. D. Lavrinenko, V. N. Pelykh, N. N. Pilipenko, N. G. Reshetnyak NSC/KIPT, Kharkov
	The paper presents the results of investigations on the zirconium specimen surface after irradiation them with an electron beam from the accelerator. The operating conditions were the following: electron energy from 7 to 80 keV, pulse duration of 15 μs, pulse frequency of 2 Hz. for two modes of the energy density on the samples, namely, 10 J/сm2 and 20 J/сm2. The experiments have demonstrated that the irradiation leads to the noticeable smoothing of the specimen surface roughness, the surface becomes smoother and unruffled. The results of investigations on the microhardness of irradiated and unirradiated areas of the zirconium specimen surface areas show that the microhardness value has been increased by ~20% of the initial value (1920 MPa) for the irradiation energy density of 10 J/cm² and by ~35% for 20 J/cm², that can be related with a different quantity of an transferred energy of the irradiated surface. By choosing the optimum electron irradiation characteristics this technique may be recommended for hardening and modification of the near-surface layer of zirconium materials applied in the nuclear-power engineering.

FRCHB03	Status of ILU-14 Electron Accelerator	electron, coupling, focusing, feedback	411
	V. S. Podobaev, V. V. Bezuglov, A. A. Bryazgin, K. N. Chernov, V. G. Cheskidov, B. L. Faktorovich, V. A. Gorbunov, I. V. Gornakov, A. V. Ivanov, E. N. Kokin, M. V. Korobeynikov, A. N. Lukin, I. Makarov, N. V. Matyash, S. A. Maximov, G. N. Ostreiko, A. D. Panfilov, V. M. Radchenko, N. D. Romashko, G. V. Serdobintsev, A. V. Sidorov, V. V. Tarnetsky, M. A. Tiunov, V. O. Tkachenko BINP SB RAS, Novosibirsk
	A new high power (up to 100 kW) industrial linear electron accelerator ILU-14 for energy of 7.5–10 MeV is under construction at Budker INP. The accelerator operates at 176 MHz with total efficiency of 26 %, its modular structure allows the electron energy and beam current to be varied within certain limits by changing the modular arrangement. The 5 MeV prototype of the accelerator was created and successfully tested in 2009. The designed average beam current of 600 mA with pulsed power of 2.5 MW and accelerating structure electron efficiency of 68 % were obtained during experiments. Applying an additional RF voltage to the electron gun cathode-grid gap allowed a beam current passing of 96 % with minor beam energy spread. The paper presents results of the numerical and experimental study of the accelerator systems together with the latest tests on the accelerator prototype.
	Slides