Keyword: plasma
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MOYBB101 Review of Laser Wakefield Accelerators electron, laser, injection, wakefield 11
 
  • V. Malka
    LOA, Palaiseau, France
  
  Funding: European Research Council for funding the PARIS ERC project (Contract No. 226424). EC FP7 LASERLABEUROPE/ LAPTECH (Contract No. 228334) EuCARD/ANAC, EC FP7 (Contract No. 227579)
This review talk will highlight the tremendous evolution of the research on laser wakefield accelerators* that has, in record time, led to the production of high quality electron beams beyond the GeV level, using compact laser systems. I will describe the path we followed to explore different injection schemes (bubble, colliding laser pulses, injection in gradient, longitudinal and transverse, ionisation injection) and I will present the most significant breakthroughs which allowed to generate stable, high peak current and high quality electron beams, with control of the charge, of the relative energy spread and of the electron energy. Modelling and experimental results will be as well reported with examples of applications**.
* V. Malka, Physics of Plasmas 19, 055501 (2012)
** V. Malka et al., Nature Physics 4, 447 (2008)
 		 
slides icon Slides MOYBB101 [14.550 MB]  
 
MOPEA031 Study of Extraction and Transport of Intense Highly Charged Ions for 18GHz SC-ECRIS at RCNP ion, extraction, cyclotron, ECR 145
 
  • T. Yorita, M. Fukuda, K. Hatanaka, K. Kamakura, S. Morinobu, A. Tamii, Y. Yasuda
    RCNP, Osaka, Japan
  
  An 18 GHz superconducting ECRIS has also been installed to increase beam currents and to extend the variety of ions, especially for highly charged heavy ions which can be accelerated by RCNP cyclotrons. The mirror magnetic field is produced with four liquid-helium-free superconducting coils and the permanent magnet hexapole is of Halbach type with 24 pieces of NEOMAX-44H material. The production development of several ions like B, O, N, Ne, Ar, Ni, Kr and Xe has been performed. Further study for its beam extraction and transport have been done in order to increase the beam injected to cyclotron. The parameters of extraction systems and electrostatic lens are optimized taking account with magnetic field leakage from AVF Cyclotron. Emittance study also has been done to see the quality of injection beam. For that purpose two types of emittance monitor have been developed. One is using three wire profile monitor and another has BPM with rotating wire for quick measurement. The details of these developments will be presented.  
 
MOPEA065 Commissioning of the Ion Source for Siemens Novel Electrostatic Accelerator ion, ion-source, extraction, electron 231
 
  • H. von Jagwitz-Biegnitz
    JAI, Oxford, United Kingdom
  • P. Beasley, O. Heid
    Siemens AG, Erlangen, Germany
  • D.C. Faircloth
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • A.J. Holmes
    Marcham Scientific Ltd, Hungerford, United Kingdom
  • R.G. Selway
    Inspired Engineering Ltd, Climping, United Kingdom
  • B. Singh, E. Zitvogel
    BNL, Upton, New York, USA
  
  Siemens is developing a novel compact DC electrostatic tandem accelerator and currently building a prototype. A dedicated H− ion source for this accelerator has been designed and built. This paper reports on some of the design features as well as results of the commissioning phase of this filament driven DC multicusp volume H− ion source. Stable H− currents of more then 300 μA at 10 keV have been extracted. This satisfies the beam current requirement of the novel accelerator.  
 
MOPEA083 Energy Modulation in Coherent Electron Cooling electron, ion, FEL, simulation 276
 
  • G. Wang, M. Blaskiewicz, V. Litvinenko
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling (CeC) relies on Debye shielding to imprint information of the ion beam to an electron beam [1]. Apart from the density modulation, Debye shielding also modulates the energy of electrons, which provides additional seeding for the free electron laser (FEL) amplifier. In this work, we show that the energy modulation of a longitudinal slice of the electrons, induced by dynamic Debye shielding of a moving ion in anisotropic electron plasma with κ-2 velocity distribution, can be expressed into a 1D integral. The results are then applied to the 1D FEL model to investigate the effects of energy modulation to the correcting force in the kicker.
[1] V.N. Litvinenko, Y.S. Derbenev, Coherent Electron Cooling, Physical Review Letters, 102 (2009) 114801. http://link.aps.org/abstract/PRL/v102/e114801 		 
 
MOPFI034 First Intense H− Beam Generated by a Microwave-driven Pure Volume Source ion, electron, ion-source, extraction 360
 
  • S.X. Peng, J. Chen, J.E. Chen, Z.Y. Guo, H.T. Ren, Zh.W. Wang, Y. Xu, T. Zhang
    PKU, Beijing, People's Republic of China
  • A.L. Zhang
    Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
  • J. Zhao
    State Key Laboratory of Nuclear Physics and Technology, Beijing, Haidian District, People's Republic of China
  
  The 2.45 GHz Electron cyclotron resonance (ECR) plasma generators have demonstrated their efficiency, reproducibility on producing H+, D+, O+, N+, He+, Ar+* and He2+ at Peking University(PKU). Recently, modifications on magnet field configuration, discharge chamber structure and extraction system have been done to set-up a microwave-driven pure volume H− ion source. First experiment was done on PKU ion source test bench at the beginning of Nov, 2012. A 15 mA H− ion beam has been produced at 40 keV by this prototype source. This paper describes the source principle and design in detail and reports on the current status of the development work.
* H. T. Ren, S. X. Peng*, P. N. Lu, S. Yan, Q. F. Zhou, J. Zhao, Z. X. Yuan, Z. Y. Guo and J. E. Chen, Rev. Sci. Instrum. 83, 02B905 (2012)
 		 
 
MOPFI035 Preliminary Results of H2+ Beam Generated by a 2.45 GHz Permanent Magnet ECR Ion Source at PKU ion, ion-source, permanent-magnet, cyclotron 363
 
  • Y. Xu, J. Chen, J.E. Chen, Z.Y. Guo, Y.T. Luo, S.X. Peng, H.T. Ren, Z.H. Wang, T. Zhang, J. Zhao
    PKU, Beijing, People's Republic of China
  • A.L. Zhang
    Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
  
  Recently, the need to build an ion source generating high current hydrogen molecular ion H2+ beam has been growing rapidly. For example, H2+ ion can be used as a pilot beam of the intense deuteron beam during the commission phase of linear accelerators to minimize the activation of components. And it is an effective way to improve the output current of cyclotrons by accelerating H2+ and stripping it into H+ at the exit of accelerator, instead of accelerating H+ beam directly. To obtain high-yield H2+ ion beam, experimental and theoretical study was carried out on the 2.45 GHz Peking University permanent magnet electron cyclotron resonance ion source (PKU PMECR). With PMECR II*, studies on the size of discharge chamber and the operation pressure were carried out to increase H2+ ion fraction. Beam analysis results prove that the H2+ can reach 40.5% with suitable operation parameters. More details will be presented in this paper.
* Zhizhong Song, Shixiang Peng et al., Rev. Sci. Instrum. 77, 03A305 (2006)
** Author to whom correspondence should be addressed. Electronic mail:
sxpeng@pku.edu.cn.
 		 
 
MOPFI047 Analysis and Design of Matching Unit for a RF Driven Plasma Source for Fusion Purpose impedance, ion, ion-source, neutral-beams 389
 
  • H.K. Yue
    Huazhong University of Science and Technology(HUST), Wuhan, People's Republic of China
  • D.Z. Chen, M. Fan, J. Huang, D. Li, X.F. Li, K.F. Liu, C.R. Wan, C. Zhou
    HUST, Wuhan, People's Republic of China
  
  A RF driven plasma exciter for producing negative ions, aiming for heating and current drive neutral beam injectors for fusion applications, is in developing in Huazhong University of Science and Technology (HUST). In order to couple the maximum RF power to the source, the matching unit is designed to match the impedance of the source to that of the RF coaxial line. Firstly, a FEM model was built to estimate the equivalent circuit parameters of the source. Numerical predictions were compared with a small experimental setup to verify the accuracy of the fem model. Based on the numerical results, the RF coil and the matching components were carefully designed. Finally, the matching circuit for the source is developed and tested. Experimental results will be presented in the full paper.  
 
MOPFI066 An Ultra-Low Energy Electron Beam Ion Trap in Shanghai electron, ion, injection, cathode 434
 
  • J. Xiao, R. Hutton, X. Jin, D. Lu, B. Tu, Y. Yang, R. Zhao, Y. Zou
    Fudan University, Shanghai, People's Republic of China
  
  Electron beam ion traps (EBITs) are very useful tools for disentanglement studies of atomic processes in plasmas. In this paper, a new ultra-low energy EBIT, SH-HtscEBIT, is reported. This EBIT can operate in the electron energy range of 30–4000 eV, with a current density of up to 100 A/cm2. The low energy limit of this machine is 30 eV, which is the lowest energy among the EBITs around the world. The maximum magnetic field in the central drift tube region of this EBIT is around 0.25 T, produced by a pair of high temperature superconductor coils. This EBIT is set up for the purpose of disentangling spectroscopic studies of edge plasmas relevant to magnetic fusion devices, and of astro-plasmas. All the elements for the spectroscopic studies can be injected through an injection system. Both the design and the performance of this EBIT are presented.  
 
MOPFI069 Preparation of the Polycrystalline Copper Photocathodes for the VELA RF Photocathode Gun gun, ion, electron, cathode 440
 
  • R. Valizadeh, A.N. Hannah, K.J. Middleman, B.L. Militsyn, T.C.Q. Noakes, R.N.C. Santer
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • M.D. Roper
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  
  The Electron Beam Test Facility (EBTF) is a high performance electron source under commissioning at ASTeC. The photoinjector of the source is based on a S-band photocathode RF gun operating with a copper photocathode which is driven by a third harmonic of Ti: Sapphire laser (266 nm). The photocathode used in the RF gun is an integrated part of the gun cavity which is polycrystalline copper disk, polished to 1um roughness, and is placed at the back wall of the first 0.5 cell in the gun cavity. In order to accomplish a procedure to activate surface prior installation, copper test samples with roughness of 0.1 um were prepared by different techniques. The best results have been obtained by ex-situ plasma cleaning in an oxygen atmosphere. Analyses showed that there was no carbon on the surface and the surface was composed of copper oxide. After heating the sample in-situ to 220 C for almost all the surface oxide was removed. For this surface a QE of 2 x10-5 was measured. Further heating to higher temperature did not result in any improvement either in surface composition nor a noticeable increase in QE. Prepared such a way operational photocathode is now under commissioning in the gun.  
 
MOPFI074 Ultracold and High Brightness Electron Source for Next Generation Particle Accelerators electron, laser, brightness, emittance 452
 
  • G.X. Xia, R. Appleby, W. Bertsche, M.A. Harvey
    UMAN, Manchester, United Kingdom
  • S. Chattopadhyay
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • S. Chattopadhyay
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • A.J. Murray
    The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
  
  The ultra-cold plasma-based electron source has recently been proposed as an alternative to the conventional photoemitters or thermionic electron guns, which are widely used in today’s particle accelerators. The advantages of the ultra-cold plasma-based electron source lie in the fact that the electron beam extracted from the cold plasma (from ionization of cold atoms) has very low electron temperature, e.g. down to 10 K, and has the potential for producing high brightness and ultra-short electron bunches. All these features are crucial for the next generation particle accelerators, e.g. free electron lasers, plasma-based accelerators and the future linear colliders. In this paper, we will introduce our proposed facility on cold electron source based at Photon Science Institute (PSI) in the University of Manchester.  
 
MOPME029 Multi-strip Current Monitor for Pulsed Laser Plasma Diagnostics ion, laser, rfq, target 538
 
  • Y. Fuwa, Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • M. Okamura
    BNL, Upton, Long Island, New York, USA
  
  A compact position-sensitive beam instrumentation devise is under development. The beam detection area of this devise is composed of multi-strip electrodes and scanned by multiplexers, which reduces the number of read-out lines and feed-through connectors. Combined with an electrostatic deflector and ToF information, this monitor can discriminate charge to mass ratios of particles. A prototype of this monitor is fabricated for measurement of ion distribution and charge state in laser induced plasma. This model has fifteen strip electrodes and the multiplexed signal and the clock signal are read out through two coaxial cables. Thus, only three cables are needed including a +5V power supply line. The test result will be presented.  
 
MOPWO002 PTCC: New Beam Dynamics Design Code for Linear Accelerators linac, space-charge, simulation, cavity 882
 
  • Y. N. Nour El-Din, T.M. Abuelfadl
    Cairo University, Giza, Egypt
  
  Funding: Work supported by the Egyptian Science and Technology Development Fund (STDF) No. 953.
A fast and accurate beam dynamics design code, named PTCC (Particle Tracking Code in C) is developed to simulate particles dynamic in linear accelerators. PTCC solves the relativistic equations of motion for the macro-particles when subjected to electromagnetic fields excited in RF cavities. The self-fields of the particles are also part of the electromagnetic fields through which the particles are tracked. Self-fields are calculated using a modified 2D cylindrically symmetric mesh based method, making use of beam and field symmetry to provide fast simulation. The code has been benchmarked with the well known code ASTRA which is used mainly in simulations of next generation FEL linacs. PTCC provides a new tool for designing buncher section of linear accelerators that convert DC beam into bunches. New buncher design tool and benchmark results of PTCC with ASTRA are presented. 		 
 
MOPWO068 Simulating Electron Cloud Evolution using Modulated Dielectric Models simulation, electron, diagnostics, proton 1043
 
  • S.A. Veitzer, P. Stoltz
    Tech-X, Boulder, Colorado, USA
  
  Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499), and the SCiDAC-3 project (DE-SC0008920)
Electron clouds can pose a serious threat to accelerator performance, and understanding cloud buildup and the effectiveness of different mitigation techniques can provide cost-saving improvements in accelerator design and fabrication. Microwave diagnostics of electron clouds are a non-destructive way to measure cloud buildup, but it is very difficult to measure the cloud density from spectral signals alone. Modeling travelling-wave rf diagnostics is very hard because of the large range of spatial and temporal scales that must be resolved to simulate spectra. New numerical models have been used to generate synthetic spectra for electron clouds when the cloud density is not changing, and results have been compared to theoretical results. Here we use dielectric models to generate spectra for clouds that evolve over many bunch crossings. We first perform detailed simulations of cloud buildup using kinetic particle models, and then use an equivalent plasma dielectric model corresponding to this density, at a finer time resolution, to compute spectra. The stability and accuracy of dielectric models that spectra can be accurately determined in these very long timescale simulations. 		 
 
MOPWO088 Semi-analytical Description of the Modulator Section of the Coherent Electron Cooling electron, shielding, hadron, simulation 1082
 
  • A. Elizarov, V. Litvinenko
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We discuss the theoretical description of the modulator section of the coherent electron cooling (CeC)*, the modern realization of the stochastic electron cooling, where the electron beam serves as a modulator and a kicker, i.e., it records the information about the hadron beam via electron density perturbations resulting from the shielding of the hadrons and then accelerates or decelerates hadrons by its electric field with respect to their velocities. To analyze the performance of the CeC shielding of a hadron in an electron beam should be computed with high precision. We propose a solution of this problem via Fourier and Laplace transforms for 1D, 2D and 3D plasmas. In some cases there are fully analytical solutions, which gave an opportunity to test semi-analytical ones involving numerical evaluations of the inverse integral transforms. Having its own practical value this solution will also serve as a testing ground for our general solution via numerical treatment of the integral equations applicable for the realistic case of the finite beam**.
* V. N. Litvinenko, Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
** A. Elizarov, V. Litvinenko, G. Wang, IPAC'12 Proceedings, weppr099 (2012). 		 
 
TUOCB102 SPARC_LAB Recent Results laser, electron, photon, FEL 1114
 
  • M. Ferrario, D. Alesini, M.P. Anania, A. Bacci, M. Bellaveglia, M. Castellano, E. Chiadroni, D. Di Giovenale, G. Di Pirro, A. Drago, A. Esposito, A. Gallo, G. Gatti, A. Ghigo, T. Levato, A. Mostacci, L. Palumbo, A.R. Rossi, B. Spataro, C. Vaccarezza, F. Villa
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    INFN-Roma II, Roma, Italy
  • G. Dattoli, E. Di Palma, L. Giannessi, A. Petralia, C. Ronsivalle, V. Surrenti
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • C. De Martinis
    INFN/LASA, Segrate (MI), Italy
  • R. Faccini
    INFN-Roma, Roma, Italy
  • M. Gambaccini
    INFN-Ferrara, Ferrara, Italy
  • D. Giulietti
    UNIPI, Pisa, Italy
  • L.A. Gizzi, L. Labate
    CNR/IPP, Pisa, Italy
  • S. Lupi
    Università di Roma I La Sapienza, Roma, Italy
  • V. Petrillo, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • J.V. Rau
    ISM-CNR, Rome, Italy
  • G. Turchetti
    Bologna University, Bologna, Italy
  
  A new facility named SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) has been recently launched at the INFN National Labs in Frascati, merging the potentialities of the an ultra-brilliant electron beam photoinjector and of a high power Ti:Sa laser. The test facility is now completed, hosting a 150 MeV high brightness electron beam injector which feeds a 12 meters long undulator. Observation of FEL radiation in variuous configurations has been performed. In parallel to that a 200 TW laser that is linked to the linac and devoted to explore laser-matter interaction, in particular with regard to laser-plasma acceleration of electrons (and protons) in the self injection and external injection modes. The facility will be also used for particle driven plasma acceleration experiments (the COMB experiment). A Thomson scattering experiment coupling the electron bunch to the high-power laser to generate coherent monochromatic X-ray radiation is also in the commissioning phase. We report in this paper the recent results obtained at the SPARC_LAB facility.  
slides icon Slides TUOCB102 [12.874 MB]  
 
TUODB202 Experiment and Numerical Simulation Results of Plasma Window simulation, vacuum, cathode, cavity 1155
 
  • K. Zhu, S. Huang, Y.R. Lu, B.L. Shi
    PKU, Beijing, People's Republic of China
  
  Funding: Supported by NSFC 91026012
A windowless vacuum seal technique has been widely researched and designed, which can connect high pressure cavity to a vacuum condition with rather little thickness of material. As a result, it will reduce most interaction with the particle beam penetrating through comparing to that of foil window. It is desired extensively in experiments using high-intensity heavy ion beams which will break foil window in a short time or in experiments which require the injecting beams with mono-energy and high purity for example. In this work, we study the plasma window in argon which is used as a windowless vacuum sealing device. A numerical 2D FLUENT-based magneto-hydrodynamic model has been developed to investigate the physical reasons of high pressure difference in plasma window. Further, preliminary experimental results are presented and discussed. 		 
slides icon Slides TUODB202 [2.180 MB]  
 
TUPEA008 Physics of the AWAKE Project wakefield, electron, laser, injection 1179
 
  • P. Muggli, E. Oz, R. Tarkeshian
    MPI, Muenchen, Germany
  • C. Bracco, E. Gschwendtner, A. Pardons
    CERN, Geneva, Switzerland
  • A. Caldwell, O. Reimann
    MPI-P, München, Germany
  • K.V. Lotov
    BINP SB RAS, Novosibirsk, Russia
  • A.M. Pukhov
    HHUD, Dusseldorf, Germany
  • J. Vieira
    IPFN, Lisbon, Portugal
  • M. Wing
    UCL, London, United Kingdom
  
  The goal of the AWKAKE collaboration is the study of plasma wakefields driven by proton (p+) bunches through experiments, simulations and theory. Proton bunches are interesting wakefield drivers because they can be ultra-relativistic (TeVs/p+) and carry large amounts of energy (>kJ). It was demonstrated in simulations* that acceleration of an electron (e-) bunch from 10GeV to >500GeV can be achieved in ~500m of plasma driven by a 1TeV, 100micron-long, bunch with 1011 p+. Such short p+ bunches do not exist today. It was suggested** that a p+ bunch long compared to the plasma period can transversely self-modulate and resonantly drive wakefields to large amplitudes (~GV/m). Initial experiments based on self-modulation instability (SMI) will use single 12cm-long CERN SPS bunches with 1-3·1011, 450GeV p+ to study physics of SMI. With a plasma density of 7·1014/cc the plasma wave and modulation period is 1.3mm. The SMI saturates after ~3m with amplitude in the GV/m range. Later a low energy (~10MeV) witness e- bunch will be injected at the SMI saturation point. Energy gain over ~7m of plasma can reach the GeV level. Translation from physics to experimental plan and setup will be presented.
* A. Caldwell et al., Nature Physics 5, 363 (2009)
** N. Kumar et al., Phys. Rev. Lett. 104, 255003 (2010) 		 
 
TUPEA016 Relativistic Theory for Laser-ion Acceleration ion, acceleration, electron, laser 1193
 
  • Y.S. Huang, Y.J. Shi, X.Z. Tang, N.Y. Wang
    CIAE, Beijing, People's Republic of China
  
  Funding: The Key Project of Chinese National Programs for Fundamental Research (973 Program) under contract No. 2011CB808104 and the Chinese National Natural Science Foundation under contract No. 11105233.
An analytical relativistic model is proposed to describe the relativistic ion acceleration in the interaction of ultra-intense laser pulses with thin-foil plasmas. It is found that there is a critical value of the ion momentum to make sure that the ions are trapped by the light sail and accelerated in the radiation pressure acceleration (RPA) region. If the initial ion momentum is smaller than the critical value, that is in the classical case of RPA, the potential has a deep well and traps the ions to be accelerated. There is a new ion acceleration region different from RPA, called ultra-relativistic acceleration, if the ion momentum exceeds the critical value. In this case, ions will experience a potential downhill. The dependence of the ion momentum and the self-similar variable at the ion front on the acceleration time has been obtained. The critical conditions of the laser and plasma parameters which identify the two acceleration modes have been achieved. No matter RPA or ultra-relativistic acceleration, the potential difference is a constant, which dedicates the maximum ion energy. 		 
 
TUPEA017 Monoenergetic Electron Beams with Ultralow Normalized Emittance Generated from Laser-Gas Interaction laser, electron, emittance, simulation 1196
 
  • D.Z. Li, J. Gao, K. Huang, J. Jiarui, Y. Ma
    IHEP, Beijing, People's Republic of China
  • L.M. Chen, W.C. Yan
    Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
  
  High quality electron bunches are generated by using 2 TW, 80 fs, high contrast laser pulses interacting with helium gas targets. In optimized condition, we get tens MeV monoenergetic electron beams with small energy spread and the normalized emittance 0.07π mm·mrad. Due to its ultra small emittance and high initial energy, such bunch is very suitable for high current linear accelerators.  
 
TUPEA018 Recent Progress of Laser Plasma Proton Accelerator at Peking University laser, proton, target, acceleration 1199
 
  • X.Q. Yan, J.E. Chen, H.Z. Fu, Y.X. Geng, Z.Y. Guo, C. Lin, Y.R. Lu, Y. Shang, Z.X. Yuan, S. Zhao, K. Zhu
    PKU, Beijing, People's Republic of China
  
  Funding: National Natural Science Foundation of China (Grant Nos.10935002, 10835003, 11025523)
Recent a project called Laser plasma Proton Accelerator (LAPA) is approved by MOST in China. A prototype of laser driven proton accelerator (1~15MeV) based on the PSA mechanism and plasma lens is going to be built at Peking University in the next five years. It can be used for the applications such as cancer therapy, plasma imaging and fast ignition for inertial confine fusion. The recent progress of LAPA is reported here. 		 
 
TUPEA019 Proton Acceleration driven by High Energy Density Electrons proton, laser, acceleration, electron 1202
 
  • S. Zhao, C. Chao, J.E. Chen, H.Z. Fu, Y.X. Geng, C. Lin, B. Liu, H. Wang, X.Q. Yan
    PKU, Beijing, People's Republic of China
  
  Resonance Electrons Driving Ion Acceleration S. Zhao, C. Lin, X. Q. Yan Institute of Heavy Ion Physics, Peking University Proton acceleration driven by resonance electrons is proposed. Energetic electron beam generated through direct laser acceleration in the near critical dense plasma is dense and directional. When interacting with a thin foil target, resonance electrons can transmit the target and drive periodical electrostatic field at the back surface, therefore protons are more efficiently accelerated in a much longer distance in propagation direction of resonance electrons, compared to the classical target normal sheath acceleration. For a Gaussian laser pulse with pulse duration of 80fs, peak intensity I=1.38*108W/cm2 , the cutoff energy of the output collimated proton beam is 14MeV, enhanced by a factor of 3 or 4. The scaling law predicts hundreds MeV Proton beam can be generated in laser intensity of 1020W/cm2.  
 
TUPEA021 Calculation of Wakefields in Plasma Filled Dielectric Capillaries Generated by a Relativistic Electron Beam wakefield, electron, positron, collider 1205
 
  • C. Li, W. Gai
    ANL, Argonne, USA
  • C. Li, C.-X. Tang, H. Zha
    TUB, Beijing, People's Republic of China
  
  In this paper we give an analytical solution of TM0n mode for wakefields generated by a relativistic electron beam passing through plasma-filled capillary waveguides. The numerical solution shows that the fields of TM0n modes could not be ignored when the plasma wave length is comparable with the effective radius of the capillary tube, which means that the boundaries are not shielded completely by plasma. Numerical examples are given in several typical cases.  
 
TUPEA029 Theory Calculation of PASER in Gas Mixture Active Medium electron, resonance, laser, wakefield 1211
 
  • X.F. Tian, C.-F. Wu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  In the PASER (particle acceleration by stimulated emission of radiation), the energy stored in an active medium transferred directly to the electron beam passing through in discrete amounts by emitting a photon when the bounded electron returns from upper to lower energy state. In this paper, the wake-field generated by a bunch of electrons traversing in an active medium has been discussed. The calculations of the development of amplitude for gas mixture active medium about CO2 and ArF were made respectively. The results show that the gradient can reach around 1GeV/m. In addition, the electron energy gain occurring as a train of electron micro-bunches traversing in gas mixture was analyzed by a two dimension model. The train of micro-bunches can obviously gain energy from the active medium and the energy exchange is linearly proportional to the interaction length d. The influence of the bunch figure and other quantities on the energy exchange occurring as a train of electron micro-bunches traversing CO2 gas mixture were investigated when the interaction length is 0.5m. The results illustrate that maximum electron energy gain can be obtained by the train of micro-bunches with optimized parameters.  
 
TUPEA035 Plasma Effect in the Longitudinal Space Charge Induced Microbunching Instability impedance, electron, space-charge, background 1220
 
  • D. Huang, Q. Gu
    SINAP, Shanghai, People's Republic of China
  • K.Y. Ng
    Fermilab, Batavia, USA
  
  Funding: National Science Foundation of China (NSFC), grant No. 11275253, and US DOE, contract DE-FG02-92ER40747.
In many cases, the longitudinal space charge (LSC) is a dominant factor to bring in the microbunching instability in the LINAC of a Free-Electron-Laser (FEL) facility. The current model of LSC impedance* derived from the fundamental electromagnetic theor** is widely used to explain the physics of the LSC-induced microbunching instability***. However, in the case of highly bright electron beams, the plasma effect starts to play a role. In this paper, the basic model of the LSC impedance including the plasma effect is built up by solving the Vlasov and Poisson equations in 6 dimensional phase space, and the investigation is done to study the modification to the gain of the instability based on the model. The solutions indicate that the gain does not only depend on the spatial information of the beam, but also on the velocity (momentum) and time information. The comparison of the gains of the microbunching instability in the LINAC of Shanghai soft X-ray Free Electron Laser Facility (SXFEL) computed by various methods is also given and the discrepancy is illustrated.
* Marco Venturini, Phys. Rev. ST Accel. Beams 11, 034401 (2008)
** J. D. Jackson, Classical Electrodynamics (Wiley, 1999)
*** Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004)
 		 
 
TUPEA045 Self-Modulation and Hosing Instability of Slac Electron and Positron Bunches in Plasmas electron, positron, wakefield, simulation 1235
 
  • J. Vieira, N.C. Lopes
    Instituto Superior Tecnico, Lisbon, Portugal
  • E. Adli, S.J. Gessner, M.J. Hogan, S.Z. Li, M.D. Litos
    SLAC, Menlo Park, California, USA
  • Y. Fang
    USC, Los Angeles, California, USA
  • C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi
    UCLA, Los Angeles, California, USA
  • P. Muggli
    MPI, Muenchen, Germany
  • O. Reimann
    MPI-P, München, Germany
  • L.O. Silva
    IPFN, Lisbon, Portugal
  
  Funding: This work has been partially supported by Humboldt Foundation.
The understanding of the self-modulation (SMI) and hosing (HI) instabilities is critical for the success of the upcoming proton driven plasma wakefield acceleration experiments at CERN*. The use of long SLAC electron and positron bunches provides the possibility of understanding experimentally the interplay between SMI and HI. In this work we perform particle-in-cell simulations with the code OSIRIS with parameters that will be available for experiments at SLAC in 2013. We show that the SMI of 20 GeV lepton bunches can grow and saturate in less than 15 cm. Up to 8 GeV energy gain/loss could be observed after a meter long plasma. The HI can also be effectively mitigated by seeding the SMI using bunches with short rise times**. We also show analytically and numerically that in the linear regime and after saturation of the SMI the HI can be suppressed by a plasma-BNS damping analogue. Several diagnostics that could be used in experiments to measure the SMI development and these effects are also explored.
*G. Xia et al., J. Plasma Phys., 1-7 (2012).
**J. Vieira et al., Phys. Plasmas 19, 063105 (2012). 		 
 
TUPEA048 Simulation of Self-modulating Particle Beams in Plasma Wakefield Accelerators wakefield, simulation, proton, electron 1238
 
  • K.V. Lotov
    BINP SB RAS, Novosibirsk, Russia
  • K.V. Lotov, A. Sosedkin
    NSU, Novosibirsk, Russia
  • E. Mesyats
    ICM&MG SB RAS, Novosibirsk, Russia
  
  Funding: The Ministry of education and science of Russia, project 14.B37.21.0784.
Controlled self-modulation of long proton or electron beams is a new trend in plasma wakefield acceleration which sets a new goal for simulation codes. Long interaction lengths (tens of meters), long beams (up to hundred of plasma wave periods), motion of plasma ions, and violation of fluid approximation are factors that makes the problem too heavy for general purpose codes. Only specialized codes can attack this problem in real geometry. We describe recent upgrades of the code LCODE which enabled simulations of long dense proton beams and report results of numerical studies of proton beam-plasma interaction in the context of AWAKE project. 		 
 
TUPEA049 Wakefields of Ultrarelativistic Bunches in Cold Magnetized Plasma wakefield, radiation, electron, acceleration 1241
 
  • S.N. Galyamin, A.V. Tyukhtin
    Saint-Petersburg State University, Russia
  
  Funding: Work is supported by Russian Foundation for Basic Research and the Dmitry Zimin "Dynasty" Foundation.
We deal with electromagnetic field of various bunches moving in a cold magnetized plasma along the external magnetic field. The main attention is paid to the case of ultrarelativistic motion. First, for the case of point charge, we obtain the approximate formulas which are valid in the far-field zone and in the vicinity of the charge trajectory. These expressions predict the beating behavior of the far field and the harmonic behavior of the near field. Moreover, the magnitude of the longitudinal components of both electric and magnetic field as well as the transversal electric field possess singularity on the charge trajectory. Second, using formulas for the point charge field as Green function, we develop an effective algorithm for calculation of the bunch wakefield. Plots of wakefields produced by typical bunches are given. Prospects of using the bunch field properties for further development of the plasma wakefield acceleration technique are discussed. 		 
 
TUPEA051 Beam Transfer Line Design for a Plasma Wakefield Acceleration Experiment (AWAKE) at the CERN SPS laser, quadrupole, instrumentation, proton 1247
 
  • C. Bracco, J. Bauche, D. Brethoux, V. Clerc, B. Goddard, E. Gschwendtner, L.K. Jensen, A. Kosmicki, G. Le Godec, M. Meddahi, C. Mutin, J.A. Osborne, K.D. Papastergiou, A. Pardons, F.M. Velotti, H. Vincke
    CERN, Geneva, Switzerland
  • P. Muggli
    MPI, Muenchen, Germany
  
  The world’s first proton driven plasma wakefield acceleration experiment is presently being studied at CERN. The experiment will use a high energy proton beam extracted from the SPS as driver. Two possible locations for installing the AWAKE facility are considered: the West Area and the CNGS long baseline beam-line. The previous transfer line from the SPS to the West Area was completely dismantled in 2000 and it would need to be fully re-designed and re-built. For this option, geometric constraints for radio protection reasons would limit the maximum proton beam energy to 300 GeV. The existing CNGS line could be used by applying only minor changes to the final part of the lattice for the final focusing and the interface between the proton beam and the laser, required for plasma ionisation and bunch-modulation seeding. The beam line design studies performed for the two options are presented.  
 
TUPEA053 Feasibility Study of the AWAKE Facility at CERN proton, electron, laser, wakefield 1253
 
  • E. Gschwendtner, C. Bracco, B. Goddard, M. Meddahi, A. Pardons, E.N. Shaposhnikova, H. Timko, F.M. Velotti, H. Vincke
    CERN, Geneva, Switzerland
  
  Plasma Wakefield acceleration is a rapidly developing field which appears to be a promising candidate technology for future high-energy accelerators. The Proton Driven Plasma Wakefield Acceleration has been proposed as an approach to eventually accelerate an electron beam to the TeV energy range in a single plasma section. To verify this novel technique, a proof-of-principle demonstration experiment, AWAKE, is proposed using 400 GeV proton bunches from the SPS. Detailed studies on the identification of the best site for the installation of the AWAKE facility resulted in proposing the CNGS facility as best location. Design and integration layouts covering the beam line, the experimental area and all interfaces and services will be shown. Among other issues, radiation protection, safety and civil engineering constraints will be raised.  
 
TUPEA055 Quasistatic Field Influence on Bunches Focusing by Wakefields in the Plasma-dielectric Waveguide wakefield, focusing, electron, acceleration 1256
 
  • R.R. Kniaziev
    KhNU, Kharkov, Ukraine
  • G.V. Sotnikov
    NSC/KIPT, Kharkov, Ukraine
  
  Funding: The research is supported in part by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522).
Acceleration of charged particles by wakefields, excited by a drive electron bunch in the dielectric waveguide, is a perspective method in accelerator physics. We have previously proposed using plasma, filling the drift channel of the dielectric structure (DS), for focusing of the accelerated bunch*. The analytical expressions, obtained for the components of the electromagnetic field, considered only the propagating wake field, and did not consider quasi-static fields of electron bunches that are important for calculating bunches dynamics. In this paper we report the result of numerical calculations of the influence of quasistatic field of bunches on focusing by wake fields in the plasma-dielectric accelerator. We refine analytical expressions for the electromagnetic field by adding components of bunch quasi-static fields and show the correlation of total force and their quasi-static components.
* R.R. Knyazev, G.V. Sotnikov. Focusing of accelerated particles by wakefields of a drive bunch in a plasma-dielectric waveguide. Proc. of IPAC2012, New Orleans, Louisiana, USA, paper weppp003.pdf 		 
 
TUPEA064 A Proposed Plasma Accelerator Research Station at CLARA Facility electron, wakefield, simulation, acceleration 1280
 
  • G.X. Xia, K. Hanahoe
    UMAN, Manchester, United Kingdom
  • D. Angal-Kalinin, J.A. Clarke, J.K. Jones, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J.D.A. Smith
    TXUK, Warrington, United Kingdom
  
  We propose a Plasma Accelerator Research Station (PARS) based at proposed FEL test facility Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury lab. The idea is to use the relativistic electron beam from CLARA, to investigate some key issues in electron beam transport and in the electron beam driven plasma wakefield acceleration, e.g. the two bunch acceleration for CLARA beam energy doubling, high transformer ratio, long bunch self-modulation and the related beam instabilities. This paper discusses the feasibility studies of electron beam parameters to meet the requirements for beam driven wakefield acceleration and the possible experiments which can be conducted at PARS beam line.  
 
TUPEA087 Experiment on Multipactor Suppression in Dielectric-loaded Accelerating Structures with a Solenoid Field multipactoring, solenoid, electron, simulation 1319
 
  • C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • C. Chang, L. Ge, L. Xiao
    SLAC, Menlo Park, California, USA
  • M.E. Conde, W. Gai, R. Konecny, J.G. Power
    ANL, Argonne, USA
  • S.H. Gold
    NRL, Washington, DC, USA
  
  Funding: US DoE SBIR Phase I project under contract #DE-SC0007629
Efforts by numerous institutions have been ongoing over the past decade to develop a Dielectric-Loaded Accelerating (DLA) structure capable of supporting high gradient acceleration when driven by an external rf source. Multipactor is the major issue limiting the gradient that was revealed in earlier experiments. A theoretical model predicts that the strength of solenoid field within an optimal range applied to DLA structures may completely block the multipactor. To demonstrate this approach, two DLA test structures have been built and the first high power test will be conducted in December 2012. The results will be reported. 		 
 
TUPEA089 Modeling and Experimental Update on Quasi-phase Matched Direct Laser Electron Acceleration In Density-modulated Plasma Waveguides laser, electron, simulation, target 1325
 
  • M.W. Lin, D.R. Abercrombie, I. Jovanovic, A. Rakhman
    Penn State University, University Park, Pennsylvania, USA
  
  Funding: This work has been supported by the Defense Threat Reduction Agency through Contract HDTRA1-11-1-0009.
Direct laser acceleration (DLA) of electrons using the axial electric field of a radially polarized, guided intense laser pulse has the potential to lead to compact laser-driven accelerators* for security and medical applications. A density-modulated plasma waveguide could be applied to extend the laser beam propagation distance and to achieve quasi-phase matching (QPM) between laser and electron pulses for efficient DLA**. We conduct numerical simulations to design the appropriate plasma structure of the waveguides and investigate the properties of accelerated electron beams. An all-optical method, based on the igniter-heater scheme for plasma waveguide fabrication, is experimentally implemented to machine the density-modulated plasma waveguides with low-Z gas targets. A novel angle-multiplexed diagnostic technique has been developed to extract the polarization state and temporal characteristics of a radially polarized femtosecond laser pulse using spatial-spectral interferometry***. The goal of our experiments is to characterize the propagation of femtosecond radially polarized pulses in plasma waveguides.
* P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000).
** M. -W. Lin and I. Jovanovic, Phys. Plasmas 19, 113104 (2012).
***P. Bowlan, et al., Opt. Exp. 14, 11892 (2006) 		 
 
TUPFI053 Transient Beam Loading Effects in Gas-filled RF Cavities for a Muon Collider cavity, ion, beam-loading, electron 1463
 
  • M. Chung, A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, USA
  • B.T. Freemire
    IIT, Chicago, Illinois, USA
  
  Funding: Research supported by the U.S. Department of Energy.
A gas-filled RF cavity can be an effective solution for the development of a compact muon ionization cooling channel. One possible problem expected in this type of cavity is the dissipation of significant RF power through the beam-induced plasmas accumulated inside the cavity (plasma loading). In addition, for the higher muon beam intensity, the effects of the beam itself on the cavity fields in the accelerating mode are non-negligible (beam loading). These beam-cavity interactions induce a transient phase which may be very harmful to the beam quality. In this study, we estimate the transient voltage in a gas-filled RF cavity with both the plasma and conventional beam loading and discuss their compensation methods. 		 
 
TUPFI058 Simulation of Beam-induced Gas Plasma in High Gradient RF Field for Muon Colliders electron, ion, simulation, electromagnetic-fields 1478
 
  • K. Yonehara, M. Chung, A.V. Tollestrup
    Fermilab, Batavia, USA
  • B.T. Freemire
    IIT, Chicago, Illinois, USA
  • R.P. Johnson, T.J. Roberts
    Muons. Inc., USA
  • R.D. Ryne
    LBNL, Berkeley, California, USA
  • V. Samulyak
    BNL, Upton, Long Island, New York, USA
  • K. Yu
    SBU, Stony Brook, USA
  
  There is a strong limit of available RF gradient in a vacuum RF cavity under magnetic fields because the magnetic field enhances a dark current density due to electron focusing and increases probability of an electric breakdown. This limits the cooling performance. A dense hydrogen gas filled RF cavity can break this limit because the gas acts as a buffer of dark current. However, RF power loading due to a beam-induced plasma in a dense gas filled RF cavity (plasma loading effect) is crucial to design the practical cavity. Experiment shows that the plasma loading can be mitigated in denser hydrogen gas and by doping a small amount of electronegative gas in the cavity. A complicate plasma chemical reaction should be dominated in such a dense hydrogen gas condition. A beam-induced plasma is simulated by taking into account the plasma chemistry to reproduce the condition by using the supercomputer at LBNL. We will also investigate the space charge effect in a dense gas in this effort.  
 
TUPFI059 Summary of Dense Hydrogen Gas Filled RF Cavity Tests for Muon Acceleration proton, electron, ion, photon 1481
 
  • K. Yonehara, M. Chung, M.R. Jana, M.A. Leonova, A. Moretti, A.V. Tollestrup
    Fermilab, Batavia, USA
  • B.T. Freemire, P.M. Hanlet, Y. Torun
    IIT, Chicago, Illinois, USA
  • R.P. Johnson
    Muons. Inc., USA
  
  Dense hydrogen gas filled RF cavity has a great potential to accelerate a large phase space muon beam in a strong magnetic field. The concept of novel RF cavity has been demonstrated by using an intense proton beam at Fermilab. The experimental result was agreed extremely well with the conventional dilute plasma physic. Based on the model, the beam-induced plasma in the gas filled RF cavity could be controlled by adding a small amount of electronegative gas in dense hydrogen gas. Overview of these experiments will be shown in this presentation.  
 
TUPFI064 Beam Induced Plasma Dynamics in a High Pressure Gas-Filled RF Test Cell for use in a Muon Cooling Channel electron, ion, cavity, proton 1496
 
  • B.T. Freemire, P.M. Hanlet, Y. Torun
    IIT, Chicago, Illinois, USA
  • M. Chung, M.R. Jana, M.A. Leonova, A. Moretti, T.A. Schwarz, A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, USA
  • M.G. Collura
    Politecnico di Torino, Torino, Italy
  • R.P. Johnson
    Muons. Inc., USA
  
  Filling an RF cavity with a high pressure gas prevents breakdown when the cavity is place in a multi-Tesla external magnetic field. The choice of hydrogen gas provides the additional benefit of cooling a beam of muons. A beam of particles traversing the cavity, be it muons or protons, ionizes the gas, creating an electron-ion plasma which absorbs energy from the cavity. The ionization rate can be calculated from a beam intensity measurement. Energy loss measurements indicate the loading per RF cycle per electron-ion pair range from 10-18 to 10-16 Joules in pure hydrogen, and 10-20 to 10-18 Joules when hydrogen is doped with dry air. The addition of an electronegative gas (oxygen) has been observed to reduce the lifetime of ionization electrons in the cavity to below 1 nanosecond. Additionally, the recombination rate of electrons and hydrogen ions has been measured to be on the order of 10-6 cubic centimeters per second. The recombination mechanism and hydrogen ion species, along with the three-body attachment process of electrons to oxygen, will be discussed.  
 
TUPME020 Design of a TeV Beam Driven Plasma-wakefield Linear Collider linac, collider, acceleration, linear-collider 1613
 
  • E. Adli
    University of Oslo, Oslo, Norway
  • W. An, C. Joshi, W.B. Mori
    UCLA, Los Angeles, California, USA
  • J.-P. Delahaye, S.J. Gessner, M.J. Hogan, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  • P. Muggli
    MPI, Muenchen, Germany
  
  Funding: This work is supported by the Research Council of Norway and U.S. Department of Energy under contract number DE-AC02-76SF00515.
A novel design of a 500 GeV c.m. beam-driven PWFA linear collider with effective accelerating gradient on the order of 1 GV/m and extendable in the multi-TeV energy range is presented. The main bunches collide in CW mode at several kHz repetition frequency. They are accelerated and focused with several GV/m fields generated in plasma cells by drive bunches with very good transfer efficiency. The drive bunches are themselves accelerated by a CW superconducting rf recirculating linac. We consider the overall optimizations for the proposed design, compare the efficiency with similar collider designs like ILC and CLIC and we outline the major R&D challenges. 		 
 
TUPME031 Considerations for a Higgs Facility Based on Laser Wakefield Acceleration laser, luminosity, collider, electron 1643
 
  • S. Hillenbrand, A.-S. Müller
    KIT, Karlsruhe, Germany
  • R.W. Aßmann, S. Hillenbrand, D. Schulte
    CERN, Geneva, Switzerland
  
  Laser Wakefield Accelerators have seen tremendous progress over the last decades. It is hoped that they will allow to significantly reduce the size and cost of a future liner collider. Based on scaling laws, laser-driven plasma accelerators are investigated as drivers for smaller scale facilities capable of producing Z and Higgs bosons.  
 
TUPWA049 Short High-Intensity Bunches for Plasma Wakefield Experiment AWAKE in the CERN SPS optics, emittance, impedance, proton 1820
 
  • H. Timko, T. Argyropoulos, H. Bartosik, T. Bohl, J. Esteban Müller, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  • A.V. Petrenko
    BINP SB RAS, Novosibirsk, Russia
  
  Obtaining the shortest possible bunch length in combination with the smallest transverse emittances and highest bunch intensity – this is the wish list of the proton-bunch driven, plasma wakefield acceleration experiment AWAKE currently under feasibility study at CERN. A few measurement sessions were conducted to determine the achievable bunch properties and their reproducibility. To obtain a short bunch length, the bunches were rotated in longitudinal phase space using the maximum available RF voltage prior to extraction. Measurements were carried out in two optics with different transition energies. The main performance limitation is longitudinal beam instability that develops during the acceleration ramp. With lower transition energy, beam stability is improved, but the bucket area is smaller for the same voltage. Based on the results obtained, we shall discuss the choice of optics, the impact of longitudinal instabilities, the importance of reproducibility, as well as options for improving the bunch parameters.  
 
TUPWO008 High-Current Beam Transport Simulations Including Gabor Lenses in Varying Non-Neutral Plasma States electron, simulation, focusing, space-charge 1892
 
  • M. Droba, H. Dinter, O. Meusel, D. Noll, U. Ratzinger, K. Schulte
    IAP, Frankfurt am Main, Germany
  
  The Gabor space charge lens has theoretically and experimentally been investigated at IAP for many years. Especially the application in high current, Low Energy Beam Transport (LEBT) sections seems efficient and attractive. The focusing properties and imaging quality of this lens type depend on the transverse and longitudinal confinement of the electron column. Different non-neutral plasma states have been observed and calculated. In general, they can be disturbed by the interaction with ion beams. This results in a shift and in a modification of the work function with a rise of aberrations and beam emittance growth. It is necessary to understand such processes for transport channels using intense ion beams to preserve the high beam brilliance. The beam transport simulations including Gabor lenses in various non-neutral plasma states will be presented and compared with experimental results.  
 
TUPWO024 The Study of a Calculation Method for Measurement of Diagnostic Neutral Beam Property neutral-beams, ion, extraction, target 1934
 
  • L.Z. Liang, C.D. Hu, J.L. Wei
    ASIPP, Hefei, People's Republic of China
  
  Funding: Supported by National Natural Science Foundation of China under Grant No. 11075183.
Considering the beam divergence and the convergence of the spherical electrode, the beam transmission model is presented, and the variation of beam edge is described by a formula, which is used to calculate the beam divergence half-angle with the experimental data obtained by the thermocouples. Assuming the beam divergence half-angle is constant in space and time, the beam profile distribution formula and variation of beam axial intensity are introduced. Taking the HT-7 Diagnostic Neutral Beam (DNB) as a reference, the divergence half-angle is calculated for the neutral beam shot 60901. The 1/e half-width of beam at collimation target calculated by formula is in agreement with that of experimental data. Variation of beam edge and axial intensity with downstream distance is estimated for HT-7 diagnostic neutral beam. 		 
 
WEXB201 Intense Highly Charged Heavy Ion Beam Production ion, ion-source, electron, heavy-ion 2077
 
  • T. Nakagawa
    RIKEN/RARF/CC, Saitama, Japan
  
  With increase of applications of heavy ions in the various fields, production of intense beam of highly charged heavy ions form the ion sources become more and more important. For example, ion sources are required to produce intense dc beams of the highly charged heavy ions for the accelerator facilities of radio isotope beam production and the intense short pulsed beams for injection into synchrotrons. Additionally, in these applications, the ion sources face several important matters to be improved for meeting the requirements, such as source lifetime, reliability, current stability, and beam emittance. For these purposes, several high performance ion sources, which include ECR ion sources, electron beam ion sources and laser ion sources, for production of the intense beam (dc and pulsed) of highly charged heavy ions have been constructed and achieved remarkable breakthrough in the past decade. In this contribution, state-of-the-art ion sources for production of intense highly charged heavy ion beams are reviewed. Future perspective is also discussed.  
slides icon Slides WEXB201 [4.395 MB]  
 
WEPWO044 RF Characterization of Niobium Films for Superconducting Cavities niobium, target, quadrupole, ion 2399
 
  • S. Aull, S. Calatroni, S. Döbert, T. Junginger, G. Terenziani
    CERN, Geneva, Switzerland
  • S. Aull
    University of Siegen, Siegen, Germany
  • A.P. Ehiasarian, G. Terenziani
    Sheffield University, Sheffield, United Kingdom
  • J. Knobloch
    HZB, Berlin, Germany
  
  Funding: Work supported by the Wolfgang-Gentner-Programme of the Bundesministerium für Bildung und Forschung (BMBF)
The surface resistance RS of superconductors shows a complex dependence on the external parameters such as temperature, frequency or radio-frequency (RF) field. The excited modes of 400, 800 and 1200 MHz allow measurements at actual operating frequencies of superconducting cavities. Niobium films on copper substrates have several advantages over bulk niobium cavities. HiPIMS (High-power impulse magnetron sputtering) is a promising technique to increase the quality and therefore the performance of niobium films. This contribution will introduce CERNs recently developed HiPIMS coating apparatus. Moreover, first results of niobium coated copper samples will be presented, revealing the dominant loss mechanisms. 		 
 
WEPFI072 Analysis of Breakdown Damage in an 805 MHz Pillbox Cavity for Muon Ionization Cooling R&D cavity, site, cathode, radiation 2857
 
  • D.L. Bowring, D. Li
    LBNL, Berkeley, California, USA
  • A. Moretti, Y. Torun
    Fermilab, Batavia, USA
  
  When operating in multi-Tesla solenoidal magnetic fields, normal-conducting cavities exhibit RF breakdown at anomalously low gradients. This breakdown behavior may be due to field-emitted electrons, focused by the magnetic field into "beamlets" with relatively large current densities. These beamlets may then cause pulsed heating and cyclic fatigue damage on cavity interior surfaces. If this model is correct, materials with long radiation lengths (relative to copper) may alleviate the problem of RF breakdown in strong magnetic fields. To study this phenomenon, RF breakdown was induced on pairs of "buttons" in an 805 MHz pillbox cavity. The shape of the buttons creates a local enhancement of the surface electric field, such that breakdown occurs preferentially on the button surface. Beryllium and copper buttons were tested in order to evaluate the effect of radiation length on RF breakdown performance. This poster presents an analysis of the damage to these buttons and suggests a path forward for future materials R&D related to breakdown in strong magnetic fields.  
 
THPFI044 NEG Thin Film Coating Development for the MAX IV Vacuum System vacuum, cathode, synchrotron, synchrotron-radiation 3385
 
  • M.J. Grabski, J. Ahlbäck, E. Al-Dmour, P.F. Tavares
    MAX-lab, Lund, Sweden
  • S. Calatroni, P. Chiggiato, P. Costa Pinto, M. Taborelli
    CERN, Geneva, Switzerland
  
  The new synchrotron radiation facility of the MAX IV laboratories is under construction and expected to deliver the first light beam in 2016. To cope with the small aperture, the intense photon bombardment and the low-pressure requirement, most of the beam pipes for the 3-GeV ring are going to be coated with Ti-Zr-V non-evaporable getter (NEG) thin films. To take advantage from the experience acquired during the construction of the Large Hadron Collider (LHC), collaboration between CERN and MAX IV Laboratories has been set up. The choice of the extruded Cu tubes, the preliminary surface treatments, the coating configuration, and the performance validation of the small-diameter vacuum chambers have been addressed. In parallel, an intense development has been tackled at CERN for the coating of vacuum chambers where photon and electron beams circulate in separate pipes. The most important results of the collaboration are presented and future perspectives pointed out.  
 
THPFI052 Application of Atmospheric Plasma-sprayed Ferrite Layers for Particle Accelerators vacuum, gun, electron, resonance 3406
 
  • F. Caspers, M. Betz, S. Federmann, M. Taborelli
    CERN, Geneva, Switzerland
  • K. K., C.A.M. Schulz
    Surface Engineering Institute, RWTH Aachen University, Aachen, Germany
  • J.X. Wu
    IMP, Lanzhou, People's Republic of China
  
  A common problem in all kind of cavity like structures in particle accelerators is the occurrence of RF-resonances. Typically, ferrite plates attached to the walls of such structures like diagnostic devices, kickers or collimators, are used to dampen those undesired modes. However the heat transfer rate from these plates to the walls is rather limited. Brazing ferrite plates to the walls is not possible in most cases due to the different thermal expansion coefficients. To overcome those limitations, atmospheric plasma spraying techniques have been investigated. Ferrite layers with a thickness from 50 micron to about 300 micron can be deposited on metallic surfaces like stainless steel exhibiting good thermal contact and still reasonable absorption properties. In this paper the technological aspects of plasma deposition are discussed and results of specifically developed RF loss measurement procedures for such thin magnetically lossy layers on metal are presented. This kind of layers can also be applied for the production of high temperature RF power loads and related examples will be shown.