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| MOPPA001 | Excitation of the Focusing Wakefields by a Relativistic Bunch in Isotropic Capillary Discharge Plasma | 242 |
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| At present work excitation of wakefields by an relativistic electron bunch in a capillary tube filled with plasma is investigated. In the approximation of constant velocity of the bunches an analytical expressions for a components of an electromagnetic field are found. Numerical calculations of excited capillary tubes fields fabricated from the alumina and the quartz is carried out. Outer diameter of a capillary tube is equal 1 mm, inner diameter is 0.4 mm. In the absence of plasma in such structure the wakefields of the THz frequencies range are excited. Longitudinal and transverse profiles of wake fields in slow wave structure which drive channel is filled with plasma are investigated in details. These profiles allow to investigate dependences of wakefields from plasma density, the sizes of dielectric structure and/or the linear sizes of an electron bunch. When comparison of these dependences, it follows that there are longitudinal positions of the test bunch relative to the drive bunch, which can provide high-gradient acceleration of charged particles and their simultaneous radial focusing. | ||
| MOPPA002 | Nonlinear Theory of Excitation of an Axially Asymmetric Wakefield in Dielectric Resonator | 245 |
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| A nonlinear self-consistent theory of excitation of an axially asymmetric wakefield by relativistic electron bunches in cylindrical dielectric resonator with a vacuum channel for the charged particles transportation through the resonator is constructed. An excited fields are presented in the form of superposition solenoidal and potential fields. The solenoidal electromagnetic fields are presented by an expansion of the required fields into solenoidal fields of the empty dielectric resonator. The potential field is presented by the eigenfunction expansion method. The dispersion equation for determination of eigenfrequencies and the equation for eigenvalues are obtained, eigenwaves, eigenfunctions and their norms are found. For an excited fields the analytical expressions, that take into account both longitudinal and transverse dynamics of bunch particles are derived. Along with the equations of motion they provide a self-consistent description of the dynamics of generated fields and bunches. The formulated nonlinear theory allows investigating numerically the nonlinear effects such as increasing of the transverse bunch size, and head-tail beam breakup instability, which occurs if the electron bunch in the structure is misaligned. | ||
| MOPPA003 | A Coaxial Two-Channel Dielectric Wakefield Structure for Two-Beam Acceleration Experiments at SLAC | 248 |
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Funding: Research is supported by U.S. Department of Energy, Office of High Energy Physics Results of analytical and numerical investigations of a coaxial dielectric wakefield accelerator structure (CDWA) for experiments at FACET (SLAC) on two-beam acceleration are presented. For these experiments it is proposed to use ~1 THz structure with two nested silica cylindrical shells having these diameters: outer shell, OD = 2 mm, ID = 1 mm; inner shell OD = 360 mkm, ID = 100 mkm. A conventional CDWA structure is energized by an annular drive bunch travelling in the annular vacuum channel. At present, FACET has no drive bunch of annular shape which is required for a CDWA. However, our analytical studies and numerical simulations prove clearly that an annular drive bunch can be substituted by a solid bunch having the same charge*. For the simulation we used the SLAC drive bunch parameters: energy is 23 GeV, charge is 3 nC, axial RMS size is 25 mkm, transverse RMS size is 10 mkm. This bunch sets up at the central channel axis an accelerating gradient of ~1 GeV/m. Questions of transverse stability of the solid drive and accelerated bunches in this dielectric accelerator structure are also discussed. *G.V.Sotnikov, J.L. Hirshfield, T.C. Marshall, S.V. Shchelkunov, "A reciprocity principle for wakefields in a two-channel coaxial dielectric structure" IPAC’12, New Orleans, May 2012, WEPPP004. |
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| MOPPA004 | Energy Spread Decreasing in Linear Mode Operating Laser Plasma Wakefield Accelerator | 251 |
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Laser plasma wakefield acceleration (LPWA)* is one of most popular novel methods of acceleration. The LPWA is very perceptively because the accelerating gradient in plasma channel can be a number of orders larger than in metal structures. But the LPWA has two serous disadvantages as very high energy spread and low part of electrons trapped into acceleration. The energy spectrum better than 10% does not observed anyone in simulations or experiments. It should be noted that the electron's beam dynamics in LPWA is different for underdense plasma (quasi linear mode) and in for dense plasma (non-linear and bubble modes). Non-linear mode is studying more intensive at present and methods of the energy spread decrease are under development **,***. But the linear LPWA mode also has interest for practical use. The rate of energy gain is very high in the linear mode also and compact laboratory scale facility could be designed to accelerate the electron beam up to a hundreds MeV. Bunching before injection into plasma channel will discuss to decrease the energy spread and to enlarge the electron trapping efficiency.
* T. Tajima, J.M. Dowson. Phys. Rev. Lett., 1979, v. 43, 4, 267. ** S.V. Bulanovet al. Physics of Plasmas, 2008, 15, 073111. *** E.Esarey et al. Phys. Rev. Lett., 1997, 79, 2682. |
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| MOPPA005 | Laser-Wakefield Acceleration with External Bunch Injection at REGAE | 254 |
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Funding: Helmholtz Alliance Short and highly intense laser pulses focused into a gas target, ionise the gas and may excite large amplitude plasma waves that support extreme electric fields (>10 GV/m) for acceleration of charged particles. The REGAE facility at DESY, which provides 2-5 MeV of ~10 fs bunches, offers the unique possibility to study the external injection of pre-accelerated electron bunches from a conventional accelerator, and their subsequent acceleration in plasma wakefields. Simulations were performed with the particle-in-cell code OSIRIS, showing a wide variety of effects which can be explored in the future at REGAE. External controlled injection allows to study effects which require precise information about the beam quality, position and momentum at the initial point of injection. Topics of a particular interest are: bunch emittance growth suppression, controlled betatron motion, and longitudinal bunch compression. |
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MOPPA006 |
Acceleration of Electron Bunches Injected into a Wake Wave | |
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| The process of trapping and acceleration of nonmonoenergetic electron bunches by a wake wave excited by a laser pulse in a plasma channel is investigated. The formula for length of a bunch in the accelerating stage as functions of its initial energy spread and initial sizes (length and cross-section radius) is derived. It is shown that there are conditions for injection of a nonmonoenergetic bunch into a wake wave at which the energy spread of a high-energy electron bunch reaches its minimum value at a certain acceleration length. The electron energy spread in the accelerated bunch can be minimized due to electron focusing in energy space. An equation that allows one to determine the acceleration length at which energy focusing occurs is derived. This length depends on the conditions of electron injection and the properties of the accelerating wakefield. An important result is that the effect of energy focusing can suppress the energy spreads related to the initial spreads of injected electrons in both coordinate and energy spaces. Due to this effect, it is possible to obtain accelerated electron bunches with energies of several GeV and relative energy spreads on the order of 0.1%. | ||
| MOPPA007 | Wakefield Produced by a Small Bunch Moving in Cold Magnetized Plasma Along the External Magnetic Field | 257 |
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Funding: The Dmitry Zimin "Dynasty" Foundation and Russian Foundation for Basic Research (Grant No. 12-02-31258). Plasma wakefield acceleration (PWFA) is a promising tool for acceleration of charged particles to high energies at relatively small lengths. Knowledge about the structure of the electromagnetic field produced by the driver bunch in plasma plays the essential role for the realization of this accelerating scheme. Constant external magnetic field which can be used for focusing the driver bunch affects the field structure essentially because plasma acquires both anisotropy and gyrotropy. However, the electromagnetic field in the latter case has not been practically investigated until present. Here we study the field produced by point charge and small bunch moving in cold magnetized plasma along the external magnetic field. We note the singular behavior of some components of the wave field produced by point charge near the charge trajectory. We also analyze the influence of the external magnetic field and bunch size on the field components. |
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| MOPPA008 | Parameter Optimization of a Rectangular Dielectric Based Wakefield Accelerating Structure | 260 |
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| With this talk, we present the algorithm and simulation results of the wakefield parametric study of the rectangular dielectric based wakefield accelerating structure. Analytical solution of the wakefield generation in the rectangular dielectric structure has been considered to achieve optimal relations between both the geometrical parameters and dielectric constant of the structure, and the beam parameters like bunch charge and bunch length. Optimization has been carried out for maximization of the accelerating gradient at the single LSM11 mode approximation. | ||
| MOPPA009 | An Analytical Approach to Solution of Self-coordinated Beam Dynamics in Dielectric Wakefield Accelerating Structures | 263 |
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| Self-coordinated transverse dynamics of the high current relativistic electronic bunches used for generation of wake fields in wakefield accelerating structures with dielectric filling is investigated. An analytical approach to solution of self-coordinated beam dynamics is developed. | ||
| MOPPA010 | Numerical and Analytical Methods of Modeling of Bunch Dynamics in Dielectric Filled Accelerating Structures | 266 |
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| RF waveguide structures are a basis for development of new generation of accelerators on the basis of a wakefield method of the charged particle acceleration, and also free electron lasers. Numerical and analytical calculation methods of Vavilov-Cherenkov radiation generated by relativistic electronic bunches in wave guides with dielectric filling, and also self-coordinated bunch dynamics in own and external fields are considered. | ||
MOPPA011 |
Physical Startup of the First Stage of the Electron Linear Acceleration LINAC-800 | |
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| It is reported on startup of the first stage of the Electron Linear Acceleration LINAC-800 at the Veksler and Baldin Laboratory of High Energy Physics of the Joint Institute for Nuclear Research. As a result of commissioning is designed and manufactured control unit PFN-modules, carried out to the launch of the first accelerating station modulator electron linear accelerator LINAC-800. Launched and debugged high-frequency master RF-system of linear electron accelerator, conducted RF-training first accelerating section. Accelerated electron beam, are its characteristics. | ||
| MOPPA012 | Optimization of Laser Radiation Pressure Accelerator for Ion Generation | 269 |
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| Compact laser-driven accelerators are an attractive alternative for monoenergetic proton and ion generation in conventional RF accelerator because the particle acceleration electric fields can reach tens GV/cm, which allows reduction of the system size. The scheme for generating quasimonoenergetic proton with Radiation Pressure Acceleration (RPA) has the potential of leading to table-top accelerators as sources for producing 50-250 MeV protons. Theoretical and computational studies of ion energy scaling of RPA are presented. 2D and 3D PIC simulations are performed to study limitations of energy gain due to Rayleigh-Taylor instability and how is the Rayleigh-Taylor instability suppressed by density fluctuations or inhomogeneities of targets. Energy transfer efficiencies and qualities of accelerated proton beams are discussed. Absolute dose, distal, penumbra of protons accelerated by PRA in a water phantom is calculated by Geant4 Monte Carlo simulations for particle therapy applications. | ||
MOPPA013 |
The Accelerating Technique Development Paradigm Changing | |
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| The continuous aspiration to increase the energy and the current of the accelerated particles remain the basic problem of the accelerating technique, but the approaches to the ways of these problem solutions are changing. The former approaches are becoming less and less effective, and look like more and more exhausted. The installations are becoming huger and the accelerator parameters, which are based on the traditional approaches, are coming to the possible limitation. It makes the developers to return to the recent past ideas, which were not been called for the use because of the non sufficient technique development The combination of the laser and plasma kinds of the charged particle acceleration including different superconductivity types is more and more attracting the accelerating technique specialists attention. Their possibilities and restrictions connected with the further progress of the accelerated particles energy and current increase are discussed. The directions of the accelerating technique development are determined not only fundamental but application level tasks and problems also. The aspiration for the charged particle energy and current increase makes to go out the parameters limitation and find the solutions there. One of the most attractive directions of the accelerating technique development is the accelerator use in electronuclear project. | ||
MOPPA014 |
Progress on Dielectric Based High Gradient Accelerator Development. | |
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Funding: Ministry of Education and Science of Russian Federation; the US Department of Energy We present here our recent results of the Euclid Techlabs LLC/AWA of Argonne National Laboratory and St.Petersburg Electrotechnical University "LETI" collaboration on wakefield high energy acceleration of electron bunches in dielectric based accelerating structures*. This program concentrates primarily on Cherenkov radiation studies providing efficient high energy generation aimed at a future ~ TeV linear collider and a X-ray FEL light sources*. We report here on our recent experiments in high power Cherenkov generation, wakefields acceleration**,***, breakdown tests and corresponding dielectric material developments and characterizations. Progress in diamond, quartz and microwave low loss ceramic structure development in GHz and THz frequency ranges is presented***. * A.Kanareykin. Journal of Physics, Conf. Ser., 236, p.012032, 2010. ** S.Antipov et al. Appl. Phys. Lett. 100, 132910, 2012. *** A.Kanareykin. AIP Conference Proceedings, v. 1299, p. 286, 2010. |
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| MOPPA015 | Proposal of Laser Ion Beam Accelerator for Inertial Fusion | 272 |
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| The inertial nuclear fusion with laser beams, relativistic electron beams, ion beams, micro-particle beams and superconducting projectiles has been and is investigated analytically and numerically calculated by various authors along years and nowadays. Starting from the record laser peak power of 1.25 PW and radiation peak intensity of 100 EW/square centimeter produced at LLNR using the chirped pulse amplification (CPA) laser technology as well as from ELI Nuclear Physics - laser system, 3 APPOLON 10 PW (150 J/ 15 fs) proposed to be realized, this paper presents the principle and the configuration of a compact ion accelerator with optical laser in an ultra-relativistic regime, for the inertial nuclear fusion. The accelerator operation principle is based on the interaction of a laser beam with plasma. Plasma is an ideal medium for the acceleration of particles because it may stand longitudinal electric fields of high values (several GV/m), approximately three orders of magnitude greater than the ones obtained with RF cavity (limited to 100 MV/m). Plasma allows the conversion of the electromagnetic field of the laser radiation into plasma waves which can capture and accelerate the charged particles. Moreover, the main system parameters of the accelerator are also presented. | ||
| MOPPA016 | Dynamics of 197Au78+ Ions Generated in Recombination with Cooling Electrons in the NICA Collider | 275 |
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| Ions 197Au78+ are generated in recombination of original bare nuclei 197Au79+ with cooling electrons in the electron cooler of the NICA Collider. The ions 197Au78+ dynamics is considered in the in energy range 1–4.5 GeV/u when ion beam is bunched with RF voltage (collision mode operation of the NICA Collider). It is shown that some part of 197Au78+ ions can be involved in synchrotron motion when other part suffers a chaotic motion regime. Most of these ions live in vacuum chamber until further recombination in to the state of 197Au77+ and leave the Collider acceptance very fast. The evolution in time of ion distribution over the Collider aperture is presented. | ||
| MOPPA017 | Collider of the NICA Accelerator Complex: Optical Structure and Beam Dynamics | 278 |
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| Accelerator complex NICA, developed in VBLHEP JINR, must provide an ion-ion (Au79 +) and ion-proton collisions at energies of 1-4.5 GeV/u, as well as experiments on collisions of polarized proton-proton and deuteron-deuteron beams. The calculations of the optical properties of superconducting collider rings have been aimed to create appropriate conditions for the collisions of beams and obtaining the required luminosity parameters in the working range of energies. The collider characteristics and the beam dynamics have been worked out in most for ion-ion mode of the complex. | ||
| MOPPA018 | Localization of the RF Breakdown in the Parallel Coupled Accelerating Structure | 281 |
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| Parallel coupled accelerating structures (PCAS) with parallel RF power feeding of accelerating cavities has some features and advantages in compare with conventional traveling wave and standing wave structures with sequential RF power feeding. Parallel feeding of accelerating cavities minimizes the RF power flow via coupling slot and determines individual behavior of each cell in the regime of RF breakdown. These features can be used for developing of high gradient accelerating structures. The experimental data of the breakdown modes in the PCAS are presented. | ||
| MOPPA019 | RF Antenna Lead | 284 |
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| RF antenna lead is described. This lead is used for RF power input to high voltage electrodes. The device consists of receiving and transmitting antennas realized as symmetrical parts of coaxial cavity with dielectric disk between the parts. Main operating characteristics are the following: high voltage is over 60 kV, coefficient of transmission at the operating frequency is over 0.97, bandpass is over 70% (at the level of -3dB). The scheme of the device, principle of work and measured results are presented. | ||
| MOPPA020 | Multipactor Discharge in eLINAC Accelerator | 287 |
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| This paper concerns numerical simulations and experimental investigation of multipacting discharge in accelerating cavities and feeding waveguide section of eLINAC accelerator. The threshold values of accelerating gradient and input power for discharge may occur in these structures have been obtained experimentally and compared to numerical predictions. Secondary emission influence on discharge behavior were also considered. | ||
| MOPPA021 | 176 MHz Solid State Microwave Generator Design | 290 |
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| This paper concerns the R&D work upon design of a compact RF amplifier to be used for linear accelerators. The machine under development will operate at 176 MHz with output power of 25 kW in continuous wave regime. It consists of 48 push-pull PCB modules (approx. 500W output power each), connected in parallel to several radial filter rings, which both allow class-F operation and combine the power from the modules, delivering it to a single 50 Ω coax cable. The CST simulations and the results of 324 MHz test prototype measurements are presented. | ||
| MOPPA022 | Status of INR DTL RF System | 293 |
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| INR Linac is in regular operation since 1993. The accelerator incorporates DTL and DAW structures operating at 198.2 MHz and 991 MHz correspondingly. Initially two types of high power vacuum tubes specially designed for INR linac (GI-54A for final amplifier and GI-51A for intermediate amplifier) were used in DTL RF power system. However production of these tubes has been terminated resulting in a need of DTL RF system upgrade. The main goal of the recent upgrade is replacement of the old tubes by modern ones. The difficulty of replacement arises due to a need to minimize mechanical changes of the existing equipment. Another goal is improving of operational reliability. The reliability depends on vacuum tube reliability and to a large extent - on crowbar operation. The results and the experience of INR DTL RF system upgrade are presented | ||
| MOPPA023 | Investigation of INR DTL RF System Operation at 100 Hz Repetition Rate | 296 |
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| INR Linac has been operating with 50 Hz beam repetition rate so far. Increasing the repetition rate up to 100 Hz is of importance as it results in doubling of the beam intensity. To solve the task several accelerator systems must be modernized but the most critical one is the DTL rf system (up to 100 MeV). The problems related to the DTL rf system repetition rate increasing are described. One of them is a 50 Hz modulation of a 100 Hz rf pulse sequence. Though the instabilities of accelerating field due to the modulation are reduced by the feedback systems, nevertheless exploration of the effect and its minimizing is of importance. The analysis of the effect is given and the results of experimental studies are presented. | ||
MOPPA024 |
Proposal of New Version of Modulator for LUE-200 LINAC | |
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| The new version of the modulator for powerful (50 - 80 MW) S-band klystron as a source of RF power for accelerating system of linac LUE-200 of IREN installation, based on modern element base is presented. By results of the analysis of design parametres and the requirements shown to the modulator, technical offers on the device, a forming line and switchboards are formulated. Settlement schemes and cost estimations of the offered technical decisions are resulted. | ||
MOPPA025 |
Characteristics Research and Improvement of the High Power S-Band Klystron RF Sources on Linacs | |
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| Results on characteristics research, parameters improvement and upgrading of high power S-band klystrons KIU-12 "AURORA" and KIU-53 "ARKHAR", executed in the process of development, implementation, industrial production and exploitation on the linear electron accelerators are presented. Data on design and research of parameters of sample quantity of high-efficiency 40 MW klystrons "ARSENAL" are also submitted. | ||
MOPPA026 |
The Deflecting Cavities (Wobbler) Assembling for High-Energy Heavy Ion Hollow Beam Formation | |
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Funding: "Rosatom", contract #N.4e.45.90.1065 The study of high-energy-density in matter (HEDM) is one of the most challenging and interesting topics in modern physics. An intense ion beam can be used to achieve low-entropy compression of a sample material like hydrogen or ice that is enclosed in a heavy cylindrical tamper shell. Such a target will be driven by a hollow beam with an annular focal spot. This experiment was called LAPLAS (Laboratory Planetary Sciences) at the FAIR project*. In the experiment, it will be possible to achieve physical conditions that exist in the interior of giant planets, Jupiter and Saturn. Another goal of the LAPLAS experiment will be to study the problem of hydrogen metallization. In order to make a hollow beam with an annular focal spot it has been proposed to rotate the ion beam around the longitudinal axis with a high frequency using a radio frequency deflecting system (Wobbler). The Wobbler consisted of two four-cell H-mode deflecting cavities with a resonant frequency of 297 MHz is under development. The deflecting cavities of the Wobbler system were manufactured and assembled. The measured electro-dynamics characteristics of the cavities as well as methods used for the cavities frequency tuning are presented. * High Energy Density Matter Research Using Intense Heavy Ion Beams at the Future FAIR Facility at Darmstadt, N A Tahir et. al., IFSA2007 |
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MOPPA028 |
Design and Simulation of 505.8 MHz Strip Line Ferrite Circulator for Indus 2 | |
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| Circulator is an amazing device which can couple the power entering in anyone of its ports to the next port in one rotation only, and offers high isolation in reverse direction. Circulators find most wide applications in RF systems as a duplexer, and as an isolator with third port terminated with matched load. In particle accelerators ferrite circulators are used for the attenuation of reflected back power from a mismatched load or cavity to RF source to avoid the damage of RF source. To meet this requirement a strip line ferrite circulator has been designed and simulated using CST MICROWAVE STUDIO at 505.8 MHz for Indus 2 applications. Circulator geometries and biasing DC fields have been optimized (above resonance), and good results are observed with high reflection of 27 dB, with 30 dB isolation and 0.4 dB insertion loss. A MATLAB program has been developed for automatic calculations of circulator geometries, for given frequency and design parameters. Also thermal analysis has been done by observing the temperature rise with input power using thermally coupled simulation in CST Microwave studio. For 1000 watt input power maximum temperature in the circulator is 79 C without any forced cooling. This paper presents the design aspects, calculations and electromagnetic and thermal simulation of ferrite circulator. | ||
MOPPA029 |
Suppression of X-Radiation from a 2 MV Ion Electrostatic Accelerator | |
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| The paper presents results from experimental studies of X-radiation from a 2 MeV ion electrostatic accelerator "Sokol" used for nuclear microprobe analysis. The radiation protection system of the accelerator was developed and tested. Tests of the system of the accelerator show that it reduces the doses rate by two orders of magnitude. Influence of magnets of the system of suppression of radiation radiation is investigational on ion-optical properties of accelerating tube. | ||
| MOPPA030 | X-ray Radiation High-Voltage Elements of the Tandem Accelerator With Vacuum Insulation | 299 |
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| In Institute of Nuclear Physics SB RAS the epithermal neutron source is entered into operation based on the tandem – accelerator with vacuum isolation. It was evaluated the accelerating installation components of a X-ray field causing dark current and breakdowns in accelerating gaps. The estimated account of equivalent doze capacity on different distances from the accelerator in the protected hall and behind its limits is made. The experimental measurements were carried out and the study results of the doze capacity dynamics are submitted, depending on change of a dark current in tandem accelerating gaps at a complete working voltage 1 MV without a beam. The spectrum of X-ray radiation is experimentally measured. It is experimentally revealed and the occurrence of powerful X-ray radiation is investigated at substantial growth of the aperture of the accelerating channel. Are offered and the changes of a design of installation for prevention of occurrence of powerful X-ray radiation are realized. The carried out research allows setting necessary parameters for designing medical installation on the basis of an accelerator - tandem with vacuum isolation with the purpose of realization in oncological clinics neutron-capture therapy of malignant tumours. | ||
| MOPPA031 | Residual Activity in Heavy-Ion Accelerators as Beam-Loss Limiting Factor | 302 |
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| Residual activity is the main beam-loss limiting factor in high-energy proton accelerators. In order to ensure 'hands-on' maintenance the losses of proton beam should be kept below 1 W/m. It has been shown in our previous publications that the beam-loss criteria for heavy-ion machines may be established by rescaling the '1 W/m criterion' for different heavy ions. For protons the scaling factor is obviously 1. Scaling factors for other ions depend on the charge-mass number of the ion and on the beam energy. For example, for U ions with energy E = 200 MeV/u the scaling factor is 60, i.e. 60 W/m losses of U beam are tolerable from the 'hands-on' maintenance point of view, whereas for U ions with E=1 GeV/u the scaling factor is just 5. In the present paper we show that this scaling factor concept has natural limits of applicability. In the case of very low beam energies or in the case of estimates of long-term accumulated residual activity the tolerable beam-loss criteria cannot be obtained by simple rescaling '1 W/m criterion' with one single number. | ||