Search

Injection of high energy beams of neutral particles is a method for plasma heating in fusion devices. The ITER injector, and its prototype MITICA (Megavolt ITER Injector and Concept Advancement), are large extrapolations from existing devices. Therefore nu merical modeling is needed to set thermo - mechanical requirements for all beam - facing components. As the power and charge deposition originates from several sources (primary beam, co - accelerated electrons, and secondary production by beam - gas, beam - surface, and electron - surface interaction), the beam propagation along the beam line is simulated by comprehensive 3D models. This paper presents a comparative study between two codes: BTR has been used for several years in the design of the ITER HNB components; the SAMANTHA code was independently developed and includes additional phenomena, like secondary particles generated by collision of beam particles with the background gas. The code comparison is valuable in the perspective of the upcoming experimental oper ations, in order to prepare a reliable numerical support to the interpretation of experimental measurements in the beam test facilities. The power density maps calculated on the Electrostatic Residual Ion Dump (ERID) is chosen as the benchmark, as they dep end on the electric and magnetic fields as well as on the evolution of the beam species via interaction with the gas. Finally the paper shows additional results provided by SAMANTHA, like the power deposition onto the Cryopumps due to secondary electrons accelerated by the ERID fringe - field

The Coherent electron Cooling (CeC) Proof of Principle (PoP) experiment is proposed to be installed in the Relativistic Heavy Ion Collider (RHIC) to demonstrate proton and ion beam cooling with this new technique that may increase the beam luminosity in certain cases, by as much as tenfold. Within the scope of this project, a 112 MHz, 2MeV Superconducting Radio Frequency (SRF) electron gun and a 704 MHz 20MeV 5-cell SRF cavity will be installed at IP2 in the RHIC ring. The superconducting RF electron gun will be cooled in a liquid helium bath at 4.4 K. The 704 MHz 5-cell SRF cavity will be cooled in a super-fluid helium bath at 2.0 K. This paper discusses the cryogenic systems designed for both cavities. For the 112 MHz cavity cryogenic system, a condenser/boiler heat exchanger is used to isolate the cavity helium bath from pressure pulses and microphonics noise sources. For the 704 MHz 5-cell SRF cavity, a heat exchanger is also used to isolate the SRF cavity helium bath from noise sources in the sub-atmospheric pumping system operating at room temperature. Detailed designs, thermal analyses and discussions for both systems will be presented in this paper.

This paper describes industrial charged particle beamline technologies and design approaches. Beamlines accommodate myriad constraints in the radioisotope production, electron beam processing, and ion implantation market segments, and some very strange yet interesting solutions result. In this paper, a detailed look at a particular injection beamline solution gives some sense of the complexity of research and development required, and the sophistication of the beamline solutions that are utilized. A brief review of beamline applications in each industrial segment follows.

High intensity Accelerator is being studied all over world for numerous applications, which includes the waste transmutation, spallation neutron source and material irradiation facilities. The R/D activities of the technology of High intensity accelerator are also developed in China for some year, and have some good facilities around China. This paper will reports the status of some high intensity accelerators and neutron source in China, which including ADS/RFQ; CARR; CSNS; PKUNIFTY & CPHS. This paper will emphatically report the Compact Pulsed Hadron Source (CPHS) led by the Department of Engineering Physics of Tsinghua University in Beijing, China.

This paper starts from a brief overview of theoretical studies of high‐gradient accelerating structures at the University of Maryland. The rest of the paper is devoted to the analysis of ion bombardment of small protrusions in such structures. First, this problem is studied analytically. Then, some results of particle‐in‐cell simulations performed with the use of code WARP are presented and discussed.

Accelerating gradient is a key parameter of the accelerating structure in large linac facilities, like future Linear Collider. In room temperature accelerating structures the gradient is limited mostly by breakdown phenomena, caused by high surface electric fields or pulse surface heating. High power processing is a necessary procedure to clean surface and improve the gradient. In the best tested X-band structures the achieved gradient is exceed 100 MV/m in of {approx}200 ns pulses for breakdown rate of {approx} 10{sup -7}. Gradient limit depends on number of factors and no one theory which can explain all sets of experimental results and predict gradient in new accelerating structure. In paper we briefly overview the recent experimental results of breakdown studies, progress in understanding of gradient limitations and scaling laws. Although superconducting rf technology has been adopted throughout the world for ILC, it has frequently been difficult to reach the predicted performance in these structures due to a number of factors: multipactoring, field emission, Q-slope, thermal breakdown. In paper we are discussing all these phenomena and the ways to increase accelerating gradient in SC cavity, which are a part of worldwide R&D program.

The use of type III–V semiconductor materials as photocathodes has in recent years become a focus for the High Energy Physics community. Once activated to a negative electron affinity (NEA) state and illuminated by a laser, these materials can be used as a high‐brightness source of both polarised and un‐polarised electrons in some modern accelerators, for example, ALICE (Accelerators and Lasers in Combined Experiments) at Daresbury Laboratory. This paper will focus on the use of gallium arsenide (GaAs) as a photocathode, and detail the reconfiguration and re‐commissioning of two vacuum systems that support standard surface science techniques such as ultraviolet/X‐ray photoelectron spectroscopy (UPS/XPS), low energy electron diffraction (LEED) and auger electron spectroscopy (AES). The paper will present details of cleaning GaAs in order to maximise quantum efficiency and will provide evidence from XPS and LEED to demonstrate what is happening at the atomic level.

This paper reports the recent activities at JAEA for the development of 1 MeV H− ion accelerator toward the ITER NBI. For the development of MAMuG accelerator, a 320 mA H− ion beam was successfully accelerated as the highest record in the world at the MeV class energy (796 keV). This was achieved by protecting the H− ion source from the high heat load by the backstream positive ions, which was produced during the high current H− ion acceleration. The SINGAP accelerator was tested at JAEA to compare the performance of the SINGAP and the MAMuG. This paper also reports the results of the SINGAP test and the comparison between the SINGAP and the MAMuG is discussed.

There have been many significant experimental and theoretical advances recently with regard to the production of relativistic electron beams using laser wakefield accelerators (LWFA) driven by high power short pulse lasers. In particular, there has been an explosion of interest in this field following the discovery of methods to generate such beams with low energy spread. In recent work by many groups around the world the energy and quality of these beams has been improved and a more complete understanding of the “bubble” regime of electron acceleration has been obtained, enabling a significant improvement in the output electron beam stability. The 2008 Advanced Accelerator Concepts workshop in Santa Cruz CA brought together the leading groups engaged in this research from around the world. This paper will summarize the major results presented at the conference. Further details on the work described here can be found in the other related papers in these proceedings.

Employment of H‐ ion sources for the LANSCE accelerator systems goes back about 20 years, to the construction of the Proton Storage Ring (PSR). The standard ion source consists of a filament driven multi‐cusp discharge vessel with a biased converter electrode for negative‐ion production and an 80‐kV extraction system feeding into a 670‐kV electrostatic pre‐accelerator. The source typically delivers 18 mA pulsed beam current into the pre‐accelerator column and reaches up to 35 days between services at 60 Hz pulse repetition rate. Recent development efforts with this source have been dedicated to improved filament material, improved cesium oven geometry and operating the source at elevated temperatures. A second line of development focuses on filament‐less devices driven by a helicon discharge. Performance data obtained with the standard source as well as key results for the helicon experiments are given in this paper; the helicon work is discussed in a separate paper in much greater detail.

This paper describes a new monochromator design for a bending magnet beamline of the Swiss Light Source synchrotron facility. The beamline optics is based on a horizontally deflecting spherical grating monochromator (SGM) with two gratings at a constant deviation angle. It covers a photon energy range from 200 eV to 1000 eV. This paper concentrates on the original flexure‐based mechanisms with partially parallel kinematics invented and designed for this monochromator, as well as on the lessons learned from the assembly and testing of the system.

In light of the recent developments with the International Linear Collider (ILC), and the recommendation to utilize “Cold” technology for this future particle accelerator, this paper will present the lessons learned from the recently concluded Spallation Neutron Source (SNS) superconducting radio frequency (SRF) cryomodule production run at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). Over the past twenty years Jefferson Lab has worked with industry to successfully design, manufacture, test and commission more SRF cryomodules than any other entity in the United States. The knowledge gained from the design and fabrication of the SNS prototype, eleven — 0.61 (medium) beta and the twelve — 0.81 (high) beta cryomodules, will prove to be an effective asset to the ILC project. After delivery of the final production cryomodule in March 2005, design and fabrication data will be collected, evaluated and presented to make this information beneficial for future particle accelerator projects. Recommendations with respect to these findings will also be presented as an integral part of this paper.

High power tests are currently being conducted on RF‐driven dielectric‐loaded accelerating (DLA) structures to determine their viability as traveling‐wave accelerators. These tests are a collaborative effort between Argonne National Laboratory (ANL) and the Naval Research Laboratory (NRL). In a previous high power test, single‐surface multipactor was reported to be capable of absorbing more than half of the RF power incident on an alumina‐based DLA structure. In this paper, we report on the most recent set of high power tests that are attempting to further understand multipactor and eventually suppress it. Several methods were employed to suppress multipactor including: the use of a magnetic field; a TIN surface coating; and a different dielectric material (Magnesium‐Calcium‐Titanate based). The effectiveness of these three methods are presented and discussed in the paper.

RF breakdown is one of the major factors determining performance of high power rf components and rf sources. RF breakdown limits working power and produces irreversible surface damage. The breakdown limit depends on the rf circuit, structure geometry, and rf frequency. It is also a function of the input power, pulse width, and surface electric and magnetic fields. In this paper we discuss multi‐megawatt operation of X‐band rf structures at pulse width on the order of one microsecond. These structures are used in rf systems of high gradient accelerators. Recent experiments at Stanford Linear Accelerator Center (SLAC) have explored the functional dependence of breakdown limit on input power and pulse width. The experimental data covered accelerating structures and waveguides. Another breakdown limit of accelerating structures was associated with high magnetic fields found in waveguide‐to‐structure couplers. To understand and quantify these limits we simulated 3D structures with the electrodynamics code Ansoft HFSS and the Particle‐In‐Cell code MAGIC3D. Results of these simulations together with experimental data will be discussed in this paper.

It's a great pleasure for me to recount the excitement and creativity of John Dawson's so called "Advanced Accelerator Years" which span the period 1979-1992. In 1979, the now famous Tajima and Dawson paper, "Laser-Electron Accelerator," appeared in the Physical Review Letters. In it, Tajima and Dawson proposed the use of a short but intense pulse to accelerate electrons by surfing on a wake produced by such a pulse in a plasma. This scheme later became known as the Laser-Wake Field Accelerator. I was a postdoctoral fellow at the National Research Council in Ottawa, Canada at the time and read it with great interest. I and my colleagues were experimentally looking at fast electron generation from high frequency (Raman, two-plasmon decay) instabilities and resonant absorption in CO2 laser-plasma interactions. We had some intriguing results on high energy electron emission from thin foils (which generated sub-critical density plasmas) that suggested that perhaps the Raman forward instability which excites a relativistic plasma wave (vph ~ c), may have been excited in the plasma. In April 1980, I came, as a Research Engineer, to the Electrical Engineering Department of UCLA to work on Laser-Plasma Interactions with Frank Chen. Our laboratory was rather modest and I was looking for something exciting to do with our limited resources. Within a very short time after arriving at UCLA, I went over to the Physics Department to meet Toshi Tajima about his 1979 paper and talk to him about the electron emission data we had on thin foils. Toshi and I walked over to John Dawson's office and he introduced me to John. I was struck by how unassuming, friendly and interested he was. He and Toshi agreed that they could simulate the Raman Forward Scattering problem using a ID PIC code. It was at that time that I first really understood the Beat-Wave Acceleration scheme, which utilized the beating pattern produced by two different frequency laser beams to resonantly excite a plasma wave. Unfortunately for me, Toshi soon left UCLA for U. T. Austin to take up a faculty position and the simulations he promised me would have to wait for almost another year. In the meantime, I went to work in our laboratory with Chris Clayton, who was a student at the time, and got our COa laser to work on multiple frequencies using an intracavity saturable absorber cell. Within a week we were exciting a "beatwave" using an arc-plasma source. We observed that the self-focusing effect was enchanced when a two frequency laser beam was sent into the plasma at the resonant density. We were baffled by the data but John Dawson had an idea of why this may have been the case. The ponderomotive force of the finite diameter longitudinal

This paper will review some of the recent developments in the area of high-brightness electron beams. Most of the paper will be devoted to emittance compensation concepts relating to high-brightness beam production in photoinjectors. Recent interpretation of emittance compensation and the residual emittance after compensation in terms of wave breaking has provided valuable insights into the process. Wave breaking also appears to have an influence on emittance growth and halo production in transport lines, which we will briefly discuss. There has been advances in understanding the emittance growth of bunches in circular motion, particularly related to the cancellation of longitudinal and transverse energy-independent forces. Finally, some non-intercepting bunch length and emittance diagnostic approaches will be reviewed.

Each major step towards higher energy particle accelerators relies on new technology. Linear colliders require beams of unprecedented brightness and stability. Instrumentation and control technology is the single most critical tool that enables linear colliders to extend our energy reach. In this paper we focus on the most challenging aspects of linear collider instrumentation systems. In the Next Linear Collider (NLC), high brightness multibunch e+/e− beams, with L±=1012 particles/pulse and σx,y∼50×5 μm, originate in damping rings and are subsequently accelerated to several hundred GeV in 2 X-band 11424 MHz linacs from which they emerge with typical σx,y∼7×1 μm. Following a high power collimation section the e+/e− beams are focused to σx,y∼300×5 nm at the interaction point. In this paper we will review the beam intensity, position and profile monitors (x, y, z), mechanical vibration sensing and stabilization systems, long baseline RF distribution systems and beam collimation hardware.

The Low Energy Demonstration Accelerator (LEDA) facility located at Los Alamos National Laboratory (LANL) accelerates protons to an energy of 6.7 MeV and current of 100 mA operating in either a pulsed or cw mode. Of key importance to the commissioning and operations effort is the Beam Position Monitor system (BPM). The LEDA BPM system uses five micro-stripline beam position monitors processed by log ratio processing electronics with data acquisition via a series of custom TMS320C40 Digital Signal Processing (DSP) boards. Of special interest to this paper is the operation of the system, the log ratio processing, and the system calibration technique. This paper will also cover the DSP system operations and their interaction with the main accelerator control system.

Theoretical and experimental research work on multi-beam klystron (MBK) conducted in Institute of Electronics, Chinese Academy of Sciences (IECAS) is described in this paper. Research progress on Interaction between multi-electron beam and microwave electric field, multi-beam cavity, filter loaded double gap cavity broadband output circuit, multi-beam electron gun, and periodic reversal focusing system is presented. Performance and measurement results of five types of MBK are also given out. The key technical problems for present MBK are discussed in this paper.

In this paper we present theoretical analysis of a recent SASE FEL experiment performed by UCLA/LANL/RRCKI/SLAC team reporting on a high power gain of about 105 at the wavelength of 12 μm. The region of physical parameters of this experiment (as well as of future X-ray FELs) does not allow to apply available analytical techniques for quantitative description of the obtained results. The analysis presented in this paper is based on the results produced by a three-dimensional, time-dependent FEL simulation code FAST. It is shown that within the limit of accuracy of the experiment obtained data fully agree with the results of numerical simulations.

This paper summarizes activation of materials, radioactive waste, sky-shine radiation, groundwater radioactivity, airborne radioactivity, beam faults, exposure of staff, and the environmental performance indicator for a high-energy synchrotron-accelerator-complex on Long Island, New York. Groundwater contamination is a particularly sensitive area of concern. The Laboratory site is located over an EPA designated sole-source aquifer system and there is significant public concern over 3H in on-site groundwater. This paper is intended to give you information about the environmental impacts of one portion of Laboratory operations: the Alternating Gradient Synchrotron (AGS) complex of accelerators that deliver protons and heavy-ions to the high-energy physics and nuclear physics communities.

The Working Group 3 papers were divided into two general categories, those related to laser-based schemes and those based on microwave technology. In the laser-based area highlights include ongoing theoretical and experimental efforts to demonstrate electron acceleration in vacuum based either on ponderomotive or nonponderomotive mechanisms. Papers on advanced issues such as staging the laser acceleration process, compensating for space charge effects, improving inverse bremsstrahlung acceleration, and possible laser linear collider designs were also presented. In the microwave area, noteworthy contributions were reviewed on slow-wave accelerating structures employing dielectric loading; smooth-wall, fast-wave structures with a helical wiggler for inverse FEL acceleration; multistaging of smooth-wall, fast-wave structures with an axial magnetic field for increased energy cyclotron autoresonance acceleration; and technological approaches for fabrication and diamond coating of W-band structures to achieve high acceleration gradients. Dielectric-loaded structures to support multimode, multibunch wakefield excitations for trailing bunch acceleration were also discussed.

In a collaborative effort with industry and several national laboratories, the Accelerator Production of Tritium (APT) facility and the Spallation Neutron Source (SNS) linac are presently being designed and developed at Los Alamos National Laboratory (LANL). The APT facility is planned to accelerate a 100-mA H{sup +} cw beam to 1.7 GeV and the SNS linac is planned to accelerate a 1- to 4-mA-average, H{sup {minus}}, pulsed-beam to 1 GeV. With typical rms beam widths of 1- to 3-mm throughout much of these accelerators, the maximum average-power densities of these beams are expected to be approximately 30- and 1-MW-per-square millimeter, respectively. Such power densities are too large to use standard interceptive techniques typically used for acquisition of beam profile information. This paper summarizes the specific requirements for the beam profile measurements to be used in the APT, SNS, and the Low Energy Development Accelerator (LEDA)--a facility to verify the operation of the first 20-MeV section of APT. This paper also discusses the variety of profile measurement choices discussed at a recent high-average-current beam profile workshop held in Santa Fe, NM, and will present the present state of the design for the beam profile measurements planned for APT, SNS, and LEDA.

The beam position monitor (BPM) system for PEP-II, the B-Factory under construction at SLAC, is described in this paper. The system must measure closed orbit for a 3-A multibunch beam and turn-by-turn position for a low-current single bunch injected in a 200-ns gap in the multibunch beam. A system that combines broadband and narrowband capabilities and provides data at high bandwidth was designed. It includes a filter-isolator box (FIB) that selects a harmonic of the bunch spacing (952 MHz) and absorbs the other frequency components; a CAMAC-based wideband IQ and a calibrator that must work even in presence of beam, correcting for electronic measurement errors. This paper describes the system requirements, the electronics design, and the laboratory tests.

The Advanced Photon Source (APS) storage ring will utilize a closed-orbit feedback system in order to produce a more stable beam. The specified orbit measurement resolution is 25 microns for global feedback and 1 micron for local feedback. The system will sample at 4 kHz and provide a correction bandwidth of 100 Hz. At this bandwidth, standard rf BPMs will provide a resolution of 0.7 micron, while specialized miniature BPMs positioned on either side of the insertion devices for local feedback will provide a resolution of 0.2 micron (1). The measured BPM noise floor for standard BPMs is 0.06 micron per root hertz mA. Such a system has been designed, simulated, and tested on a small scale (2). This paper covers the actual hardware design and layout of the entire closed-loop system. This includes commercial hardware components, in addition to many components designed and built in-house. The paper will investigate the large-scale workings of all these devices, as well as an overall view of each piece of hardw...

This paper summarizes the main discussions of the Working Group on the Production and Dynamics of High Brightness Beams. The following topics are covered in this paper: proposed new electron sources and needed research on existing sources, discussions on issues relating to the description of phase space on non-thermalized electron beam distributions and the theoretical modeling on non-thermalized electron beam distributions, and the present status of the theoretical modeling of beam transport in bends.

The paper describes an axisymmetric noncesium hydrogen ion source for accelerator applications. The ion source electrode system is designed to aim a special variation of the local plasma parameters and accordingly quasi‐independent optimization of the negative ion generation and transportation to the emission slit. In the source a cold‐cathode inverse magnetron initiates discharge generating periphery plasma with high‐energy electrons and an axial plasma with low‐energy electrons, the two plasma regions being separated by a magnetic filter. The negative ions are extracted axially along the magnetic field lines to avoid the increase in the beam phase space due to the lateral drift of the H− ions in the crossed electric and magnetic fields. The electron emission is suppressed due to different Larmor radii of electrons and negative ions. The magnetized electrons are sent to the emitter electrode. For the current pulse length of 10−3 s and repetition rate about 10 Hz the beam current is 3.10−2 A with energy of 100 keV. The emission current density reaches ∼250 mA/cm2. The ion‐to‐electron current ratio is 1/7. The gas flow through the emission slit is 6⋅10−5 m3⋅Pa/pulse. The discharge, emission, etc. parameters of the source are presented in this paper.

This paper describes three embodiments of the ubitron (FEL) amplifier that will be analyzed for possible use on the NLC. The design frequency and power are 11.424 GHz and 200 MW peak rf output power. The baseline against which these conceptual designs are to be evaluated is the PPM‐focused 50‐MW SLAC klystron, which in simulation shows 65% efficiency. (See paper in this conference by Ken Eppley.) In order to remain competitive in cost and power consumption, only ubitron beam‐wave configurations that can use permanent‐magnet wigglers are considered.

This paper is a preliminary sketch of a conception to develop the ‘‘ultimate safety reactor’’ using modern reactor and accelerator technologies. This approach would not require a long‐range R&D program. The ultimate safety reactor could produce heat and electric energy, expand the production of fuel, or be used for the transmutation of long‐lived wastes. The use of the combined double molten salt reactor system allows adequate neutron multiplication to permit using an electron accelerator for the initial neutron flux. The general parameters of such a system are discussed in this paper.

The paper presents a retrospective view on the appearance and early development of Resonance Ionization Spectroscopy (RIS) and briefly reviews its basic principles and unique characteristics. Most of the paper concentrates on RIS applications that are most active at present time including on‐line facilities with particle accelerators, counting noble gas atoms, ultrasensitive and highly selective techniques, analytical systems which use RIS in combination with thermal atomization (TARIS), laser atomization (LARIS), ion sputtering (SIRIS) and collisional ionization (LEI).

The B‐Factory is a future plan, requiring an energy upgrade of the KEK linac from 2.5 GeV to 8.0 GeV (KEKB Project). This paper describes the recent development of an S‐band high‐power pulse klystron to be used as the PF‐linac rf‐source of the B‐Factory. This tube is a modified version of the existing 30‐MW tube, which produces 51 MW at a 310 kV beam voltage by optimizing the focusing magnetic field. In order to increase the reliability, the cathode diameter, the gun housing, and the insulation ceramic‐seal were enlarged. This tube was redesigned so as to have the same characteristics as the test results of 30‐MW tubes at a higher applied voltage without changing the rf interaction region. Four prototype tubes have been manufactured; final test results showed that these new tubes produce an output power of more than 50 MW at 310 kV with an efficiency of 46%. Recently this tube has produced more than 60 MW at a 350 kV beam voltage for a demonstration test. A comparison between the FCI‐code prediction and the test results is also given in this paper.

The Advanced Light Source (ALS), a third‐generation synchrotron light source, has been recently commissioned. Beam diagnostics were very important to the success of the operation. Each diagnostic system is described in this paper along with detailed discussion of its performance. Some of the systems have been in operation for two years. Others, in the storage ring, have not yet been fully commissioned. Those systems were, however, working well enough to provide the essential information needed to store beam. The devices described in this paper include wall current monitors, a beam charge monitor, a 50 ohm Faraday cup, dc current transformers, broad‐band striplines, fluorescent screens, beam collimators and scrapers, and beam position monitors. Also, the means by which waveforms are digitized and displayed in the control room is discussed.

The paper is divided into two parts. In the first, the overall layout of HERA and its main parameters are discussed, followed by a brief review of the preaccelerators. The status of the electron and proton rings is followed by the performance of HERA as a collider. The second part opens with a description of the two detectors, H1 and ZEUS, followed by a discussion of experimental conditions. The paper ends with a presentation of the first physics results from both experiments.

This paper will attempt to summarize the activities related to accelerator simulation at the SSC laboratory during the recent past. Operational simulations including injection, extraction, and correction, performance prediction of a specified lattice design, in particular, the effect of higher‐order multipoles on linear aperture and the effect of power supply ripple on emittance growth in the collider, and lastly, the development and application of advanced techniques to particle tracking, e.g., parallel processing and mapping techniques will be discussed in this paper.

In this paper Helical Electrostatic Quadrupole (HESQ) channel is suggested for low energy beam transport of H− beams from ion source to the RFQ. Being an electrostatic focusing lens, the HESQ avoids neutralization time. The HESQ lenses provide stronger first‐order focusing in contrast to weak second‐order focusing of einzel lenses and is also stronger in focusing than the alternating gradient focusing. In this paper, we will present analytical formalism for such channel and results of PIC simulation with space charge.

The PIP2IT test accelerator is under construction at Fermilab. Its ion source and Low Energy Beam Transport (LEBT) in its initial (straight) configuration have been commissioned to full specification parameters. This paper introduces the LEBT design and summarizes the outcome of the commissioning activities., Comment: 11 p

This paper describes the method used to identify the parameters required for the insulation gas system. This locally designed low energy electron accelerator with the present energy of 140 keV will be upgraded to 300 keV. The corona discharge will occur with the increment of beam energy; therefore insulation gas system is required to prevent this phenomenon. The corona discharge will disrupt the beam energy and harmful to the nearby devices due to the sparkling current. Therefore, a pressure vessel comprises of the few ten bar insulation gas has been designed to avoid the corona effect. As a result, the insulation species gas of nitrogen with the required pressure has been selected and identified based on its flexibility and toxicity

Demonstration of a stand-alone practical dielectric laser accelerator (DLA) requires innovation in two major critical components: high-current ultra-low-emittance cathodes and efficient laser accelerator structures. LANL develops two technologies that in our opinion are applicable to the novel DLA architectures: diamond field emitter array (DFEA) cathodes and additive manufacturing of photonic band-gap (PBG) structures. This paper discusses the results of testing of DFEA cathodes in the field-emission regime and the possibilities for their operation in the photoemission regime, and compares their emission characteristics to the specific needs of DLAs. We also describe recent advances in additive manufacturing of dielectric woodpile structures using a Nanoscribe direct laser-writing device capable of maskless lithography and additive manufacturing, and the development of novel infrared dielectric materials compatible with additive manufacturing.

The ability to engineer cathodes at the nano-scale have opened new possibilities such as enhancing quantum efficiency via surface-plasmon excitation, forming ultra-low-emittance beams, or producing structured electron beams. In this paper, we present numerical investigations of the beam dynamics associated with this class of cathode in the weak- and strong-field regimes. We finally discuss the possible applications of some of the achievable cathode patterns when coupled with other phase space manipulations.

In order to compare brightnesses of beams produced by different ion sources, a transverse emittance evaluation procedure with consistency and small ambiguity for different background noises is required. The procedure to evaluate emittances of beams produced by the Japan Proton Accelerator Research Complex (J-PARC) cesiated RF-driven Hˉ ion source is presented in this paper. The ambiguity in emittance evaluations is eliminated by defining uniquely 100% and 95% beams with a reasonably corrected beam-signal base-level. Two 95%-beam transverse normalized root mean square emittances of beams, which are produced with almost the same 2-MHz RF power and cesiation condition but with different background noise, are estimated as almost the same values by this procedure.

In the third generation light source, photon beam position stability is critical issue on user experiment. Generally photon beam position monitors have been developed for the detection of the real photon beam position and the position is controlled by feedback system in order to keep the reference photon beam position. In the PLS-II, photon beam position stability for front end of particular beam line, in which photon beam position monitor is installed, has been obtained less than rms 1μm for user service period. Nevertheless, detail analysis for photon beam position data in order to demonstrate the performance of photon beam position monitor is necessary, since it can be suffers from various unknown noises. (for instance, a back ground contamination due to upstream or downstream dipole radiation, undulator gap dependence, etc.) In this paper, we will describe the start to end study for photon beam position stability and the Singular Value Decomposition (SVD) analysis to demonstrate the reliability on photon beam position data.

We present recent results from the Mainz Microtron MAMI, which is a high intensity electron accelerator with (polarized) beam energies up to 1.6 GeV. Currently, two major experiments are operated at MAMI. The A1 spectrometer setup is ideally suited for high-resolution electron scattering experiments, which recently led to highly competitive results on electromagnetic form factors and dark photon searches. The second experiment is the Crystal Ball/TAPS calorimeter setup (A2 collaboration), which is operated at the tagged photon beam line. At A2, the baryon spectrum in the low-energy region is investigated in photo-production experiments. A polarized target for longitudinal and transversal beam polarization in combination with the polarized beam does not only allow for experiments in this field, but also opens the avenue for investigations of the polarizabilities of the nucleons, for which new results are presented in this paper. In addition, the high rate of pseudoscalar mesons produced via photo-productio...

The proposed Advanced Photon Source (APS) upgrade from a double-bend achromats (DBA) to multi-bend achromats (MBA) lattice with ring energy change from 7 GeV to 6 GeV and beam current from 100 mA to 200 mA poses new challenges for front ends. All front ends must be upgraded to fulfill the following requirements: 1) handle the high heat load from two insertion devices in either inline or canted configuration, 2) include a clearing magnet in the front end to deflect and dump any electrons in case the electrons escape from the storage ring during swap-out injection with the safety shutters open, 3) incorporate the next generation x-ray beam position monitors (XBPMs) into the front end to meet the new stringent beam stability requirements. This paper presents the evaluation of the existing APS front ends and standardizes the insertion device (ID) front ends into two types: one for the single beam and one for the canted beams. The conceptual design of high heat load front end (HHLFE) and canted undulator front...

The plan for beamlines in Phase II at Taiwan Photon Source is to construct two new BioSAXS and nano-ARPES beamlines. A highly brilliant light source can be produced with a cryogenic undulator, and many synchrotron facilities have been developed and operated with these in their storage rings. The development of a cryogenic undulator became a target for a light source in TPS phase II. A cryogenic undulator with period of length 15 mm will be made in a hybrid magnetic structure, and use PrFeB permanent-magnet materials. A maximum magnetic field 1.31 T is estimated at gap 4 mm and temperature about 100 K. The spectral performance of a TPS cryogenic undulator is presented in this paper.

National Synchrotron Light Source-II (NSLS-II) is the latest storage ring of 3 GeV energy at the Brookhaven National Laboratory (BNL). The horizontal emittance of the electron beam with the currently installed six damping wigglers is 0.9 nm.rad, which could be further reduced to 0.5 nm.rad with more insertion devices (IDs). With only one RF cavity the beam current is restricted to 200 mA. Five hundred mA operation is envisaged for next year with an addition of the second cavity. Six (plus two branches) beamlines have been commissioned in the initial phase of the project. In July 2015, three NIH funded beamlines called “Advanced Beamlines for Biological Investigations with X-rays” (ABBIX) will be added for operation. This paper describes the experiences of ID development, installation, and commissioning for the NSLS-II project as well as our future plans to improve the performance of the facility in terms of source development.

This paper describes the method to identify the magnetic coil parameters of the scanning system. This locally designed low energy electron accelerator with the present energy of 140 keV will be upgraded to 300 keV. In this accelerator, scanning system is required to deflect the energetic electron beam across a titanium foil in vertical and horizontal direction. The excitation current of the magnetic coil is determined by the energy of the electron beam. Therefore, the magnetic coil parameters must be identified to ensure the matching of the beam energy and excitation coil current. As the result, the essential parameters of the effective lengths for X-axis and Y-axis have been found as 0.1198 m and 0.1134 m and the required excitation coil currents which is dependenton the electron beam energies have be identified.

The transformer ratio of collinear beam-driven acceleration techniques can be significantly improved by shaping the current profile of the drive bunch. To date, several current shapes have been proposed to increase the transformer ratio and produce quasi-uniform energy loss within the drive bunch. Some of these tailoring techniques are possible as a result of recent beam-dynamics advances, e.g., transverse-to-longitudinal emittance exchanger. In this paper, we propose an alternative class of longitudinal shapes that enable high transformer ratio and uniform energy loss across the drive bunch. We also suggest a simple method based on photocathode-laser shaping and passive shaping in wakefield structure to realize a shape close to the theoretically optimized current profiles.

A major project is underway at Diamond Light Source to remove one of the 24 Double Bend Achromat (DBA) Storage Ring cells and replace it with a Double Double Bend Achromat (DDBA). In this way a new Insertion Device (ID) straight can be created and so ID light can be produced and delivered to a beamline previously only capable of receiving Bending Magnet (BM) radiation. This project is in support of the micro-focus Protein Crystallography (MX) beamline VMX-m which is scheduled to take users towards the end of 2017. This paper describes the Engineering Design of the DDBA project in more detail and gives the current status of the project.

Crystal channeling technology has offered various opportunities in the accelerator community with a viability of ultrahigh gradient (TV/m) acceleration for future HEP collider. The major challenge of channeling acceleration is that ultimate acceleration gradients might require a high power driver in the hard x-ray regime (∼ 40 keV). This x-ray energy exceeds those for x-rays as of today, although x-ray lasers can efficiently excite solid plasma and accelerate particles inside a crystal channel. Moreover, only disposable crystal accelerators are possible at such high externally excited fields, which would exceed the ionization thresholds which destroy the atomic structure, so acceleration will take place only in a short time before full dissociation of the lattice. Carbon-based nanostructures have great potential with a wide range of flexibility and superior physical strength, which can be applied to channeling acceleration. This paper presents a beam-driven channeling acceleration concept with CNTs and di...

Inductive Output Tube (IOT) is an amplifier that usually operates in UHF range. It is an electron tube whose basic structure is similar to conventional vacuum devices. This device is widely used in broadcast applications but is now being explored for scientific applications also specifically, particle accelerators and fusion plasma heating purposes. The paper describes the design approach of a spherical gridded electron gun of a 500 MHz, 100 kW CW power IOT. The electron gun structure has been simulated and optimized for operating voltage and current of 40kV and 3.5 A respectively. The electromagnetic analysis of this spherical electron gun has been carried out in CST and TRAK codes.