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Deng ZG, Zhang ZM, Zhang B, He SK, Teng J, Hong W, Dong KG, Wu YC, Zhu B, Gu YQ. Large-charge quasimonoenergetic electron beams produced by off-axis colliding laser pulses in underdense plasma. Phys Rev E 2017; 95:023206. [PMID: 28297850 DOI: 10.1103/physreve.95.023206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Indexed: 11/07/2022]
Abstract
Electrons can be efficiently injected into a plasma wave by colliding two counterpropagating laser pulses in a laser wakefield acceleration. However, the generation of a high-quality electron beam with a large charge is difficult in the traditional on-axis colliding scheme due to the growth of the electron beam duration coming from the increase of the beam charge. To solve this problem, we propose an off-axis colliding scheme, in which the collision point is away from the axis of the driver pulse. We show that the electrons injected from the off-axis region are highly concentered on the tail of the bubble even for a large trapped charge, thus feeling almost the same accelerating field. As a result, quasimonoenergetic electron beams with a large charge can be produced. The validity of this scheme is confirmed by both the particle-in-cell simulations and the Hamiltonian model. Furthermore, it is shown that a Laguerre-Gauss (LG) laser can be adopted as the injection pulse to realize the off-axis colliding injection in three dimensions symmetrically, which may be useful in simplifying the technical layout of the real experiment setup.
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Affiliation(s)
- Z G Deng
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China
| | - Z M Zhang
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China
| | - B Zhang
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China
| | - S K He
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China
| | - J Teng
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China
| | - W Hong
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China
| | - K G Dong
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China
| | - Y C Wu
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.,IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China
| | - B Zhu
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China
| | - Y Q Gu
- Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900, People's Republic of China.,IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China
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Yu LL, Esarey E, Schroeder CB, Vay JL, Benedetti C, Geddes CGR, Chen M, Leemans WP. Two-color laser-ionization injection. PHYSICAL REVIEW LETTERS 2014; 112:125001. [PMID: 24724654 DOI: 10.1103/physrevlett.112.125001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Indexed: 06/03/2023]
Abstract
A method is proposed to generate femtosecond, ultralow emittance (∼10-8 m rad), electron beams in a laser-plasma accelerator using two lasers of different colors. A long-wavelength pump pulse, with a large ponderomotive force and small peak electric field, excites a wake without fully ionizing a high-Z gas. A short-wavelength injection pulse, with a small ponderomotive force and large peak electric field, copropagating and delayed with respect to the pump laser, ionizes a fraction of the remaining bound electrons at a trapping wake phase, generating an electron beam that is accelerated in the wake.
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Affiliation(s)
- L-L Yu
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA and Department of Physics, University of California, Berkeley, California 94720, USA and Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - E Esarey
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C B Schroeder
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J-L Vay
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C Benedetti
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C G R Geddes
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - M Chen
- Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - W P Leemans
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA and Department of Physics, University of California, Berkeley, California 94720, USA
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3
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Kotaki H, Daito I, Kando M, Hayashi Y, Kawase K, Kameshima T, Fukuda Y, Homma T, Ma J, Chen LM, Esirkepov TZ, Pirozhkov AS, Koga JK, Faenov A, Pikuz T, Kiriyama H, Okada H, Shimomura T, Nakai Y, Tanoue M, Sasao H, Wakai D, Matsuura H, Kondo S, Kanazawa S, Sugiyama A, Daido H, Bulanov SV. Electron optical injection with head-on and countercrossing colliding laser pulses. PHYSICAL REVIEW LETTERS 2009; 103:194803. [PMID: 20365929 DOI: 10.1103/physrevlett.103.194803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Indexed: 05/29/2023]
Abstract
A high stability electron bunch is generated by laser wakefield acceleration with the help of a colliding laser pulse. The wakefield is generated by a laser pulse; the second laser pulse collides with the first pulse at 180 degrees and at 135 degrees realizing optical injection of an electron bunch. The electron bunch has high stability and high reproducibility compared with single pulse electron generation. In the case of 180 degrees collision, special measures have been taken to prevent damage. In the case of 135 degrees collision, since the second pulse is countercrossing, it cannot damage the laser system.
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Affiliation(s)
- H Kotaki
- Advanced Photon Research Center, Japan Atomic Energy Agency, Kizugawa, Kyoto, Japan
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Cormier-Michel E, Shadwick BA, Geddes CGR, Esarey E, Schroeder CB, Leemans WP. Unphysical kinetic effects in particle-in-cell modeling of laser wakefield accelerators. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:016404. [PMID: 18764064 DOI: 10.1103/physreve.78.016404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 04/29/2008] [Indexed: 05/26/2023]
Abstract
Unphysical heating and macroparticle trapping that arise in the numerical modeling of laser wakefield accelerators using particle-in-cell codes are investigated. A dark current free laser wakefield accelerator stage, in which no trapping of background plasma electrons into the plasma wave should occur, and a highly nonlinear cavitated wake with self-trapping, are modeled. Numerical errors can lead to errors in the macroparticle orbits in both phase and momentum. These errors grow as a function of distance behind the drive laser and can be large enough to result in unphysical trapping in the plasma wake. The resulting numerical heating in intense short-pulse laser-plasma interactions grows much faster and to a higher level than the known numerical grid heating of an initially warm plasma in an undriven system. The amount of heating, at least in the region immediately behind the laser pulse, can, in general, be decreased by decreasing the grid size, increasing the number of particles per cell, or using smoother interpolation methods. The effect of numerical heating on macroparticle trapping is less severe in a highly nonlinear cavitated wake, since trapping occurs in the first plasma wave period immediately behind the laser pulse.
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Thomas AGR, Murphy CD, Mangles SPD, Dangor AE, Foster P, Gallacher JG, Jaroszynski DA, Kamperidis C, Lancaster KL, Norreys PA, Viskup R, Krushelnick K, Najmudin Z. Monoenergetic electronic beam production using dual collinear laser pulses. PHYSICAL REVIEW LETTERS 2008; 100:255002. [PMID: 18643668 DOI: 10.1103/physrevlett.100.255002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2007] [Indexed: 05/26/2023]
Abstract
The production of monoenergetic electron beams by two copropagating ultrashort laser pulses is investigated both by experiment and using particle-in-cell simulations. By proper timing between guiding and driver pulses, a high-amplitude plasma wave is generated and sustained for longer than is possible with either of the laser pulses individually, due to plasma waveguiding of the driver by the guiding pulse. The growth of the plasma wave is inferred by the measurement of monoenergetic electron beams with low divergence that are not measured by using either of the pulses individually. This scheme can be easily implemented and may allow more control of the interaction than is available to the single pulse scheme.
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Affiliation(s)
- A G R Thomas
- Blackett Laboratory, Imperial College London SW7 2BZ, United Kingdom
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Kotaki H, Oishi Y, Nayuki T, Fujii T, Nemoto K, Nakajima K. Focusing quality of a split short laser pulse. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:036102. [PMID: 17411227 DOI: 10.1063/1.2712939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
For multiple laser pulse experiments, it is necessary to split a laser pulse. In order to split a short laser pulse without stretching the pulse width, the laser pulse should not pass through thick materials. For this reason, a pellicle beam splitter (BS) and/or a mirror with a hole are required as a BS for the short laser pulse. The focusing qualities of the laser pulse after passing through the pellicle BS and the mirror with a hole are the same as without the BS's. The laser pulse quality reflected by the BSs should be considered for the laser pulse. A pellicle BS is a thin foil, so, it is weak against vibrations. One should be careful about airflows and isolation from vibration sources. The spot size of the reflected laser pulse is consistent with the size reflected by a normal mirror. The energy loss is about 10% compared with a normal mirror. A mirror with a hole is strong against external vibrations. The reflected laser pulse has a doughnut shape. The reflected laser pulse is interfered due to the shape. In order to cleanly focus the laser pulse, the inside size of the doughnut should be smaller than a half size of the outside portion of the doughnut.
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Affiliation(s)
- Hideyuki Kotaki
- Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemidai, Kizugawa, Kyoto 619-0215, Japan.
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Leemans W, Esarey E, Geddes C, Schroeder C, Tóth C. Laser guiding for GeV laser-plasma accelerators. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2006; 364:585-600. [PMID: 16483950 DOI: 10.1098/rsta.2005.1724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Guiding of relativistically intense laser beams in preformed plasma channels is discussed for development of GeV-class laser accelerators. Experiments using a channel guided laser wakefield accelerator at Lawrence Berkeley National Laboratory (LBNL) have demonstrated that near mono-energetic 100 MeV-class electron beams can be produced with a 10 TW laser system. Analysis, aided by particle-in-cell simulations, as well as experiments with various plasma lengths and densities, indicate that tailoring the length of the accelerator, together with loading of the accelerating structure with beam, is the key to production of mono-energetic electron beams. Increasing the energy towards a GeV and beyond will require reducing the plasma density and design criteria are discussed for an optimized accelerator module. The current progress and future directions are summarized through comparison with conventional accelerators, highlighting the unique short-term prospects for intense radiation sources based on laser-driven plasma accelerators.
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Affiliation(s)
- Wim Leemans
- Lawrence Berkeley National Laboratory LOASIS Program, Accelerator and Fusion Research Division Berkeley, CA 94720, USA.
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Fubiani G, Esarey E, Schroeder CB, Leemans WP. Improvement of electron beam quality in optical injection schemes using negative plasma density gradients. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:026402. [PMID: 16605460 DOI: 10.1103/physreve.73.026402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Indexed: 05/08/2023]
Abstract
Enhanced electron trapping using plasma density down-ramps as a method for improving the performance of laser injection schemes is proposed and analyzed. A decrease in density implies an increase in plasma wavelength, which can shift a relativistic electron from the defocusing to the focusing region of the accelerating wakefield, and a decrease in wake phase velocity, which lowers the trapping threshold. The specific method of two-pulse colliding pulse injector is examined in detail using a three-dimensional test particle tracking code. A density down-ramp with a change of density on the order of tens of percent over distances greater than the plasma wavelength leads to an enhancement of charge by two orders in magnitude or more, up to the limits imposed by beam loading. The accelerated bunches are ultrashort (fraction of the plasma wavelength--e.g., approximately 5 fs), high charge ( > 20 pC at modest injection laser intensity approximately 10(17) W/cm(2)), with a relative energy spread of a few percent at a mean energy of approximately 25 MeV, and a normalized root-mean-square emittance of the order of 0.5 mm mrad.
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Affiliation(s)
- G Fubiani
- Ernest Orlando Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, USA
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Hafz N, Hur MS, Kim GH, Kim C, Ko IS, Suk H. Quasimonoenergetic electron beam generation by using a pinholelike collimator in a self-modulated laser wakefield acceleration. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:016405. [PMID: 16486286 DOI: 10.1103/physreve.73.016405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Indexed: 05/06/2023]
Abstract
A relativistic electron bunch with a large charge (>2 nC) was produced from a self-modulated laser wakefield acceleration configuration. For this experiment, an intense laser beam with a peak power of 2 TW and a duration of 700 fs was focused in a supersonic He gas jet, and relativistic high-energy electrons were observed from the strong laser-plasma interaction. By passing the electron bunch through a small pinholelike collimator, we could generate a quasimonoenergetic high-energy electron beam, in which electrons within a cone angle of 0.25 mrad (f/70) were selected. The beam clearly showed a narrow-energy-spread behavior with a central energy of 4.3 MeV and a charge of 200 pC. The acceleration gradient was estimated to be about 30 GeV/m. Particle-in-cell simulations were performed for comparison study and the result shows that both the experimental and simulation results are in good agreement and the electron trapping is initiated by the slow beat wave of the Raman backward wave and the incident laser pulse.
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Affiliation(s)
- N Hafz
- Center for Advanced Accelerators, Korea Electrotechnology Research Institute, Changwon 641-120, Korea
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Fubiani G, Esarey E, Schroeder CB, Leemans WP. Beat wave injection of electrons into plasma waves using two interfering laser pulses. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 70:016402. [PMID: 15324173 DOI: 10.1103/physreve.70.016402] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2003] [Indexed: 05/24/2023]
Abstract
An electron injector concept that uses a single injection laser pulse colliding with a pump laser pulse in a plasma is analyzed. The pump pulse generates a large amplitude laser wakefield (plasma wave). The counterpropagating injection pulse collides with the pump laser pulse to generate a beat wave with a slow phase velocity. The ponderomotive force of the slow beat wave is responsible for injecting plasma electrons into the wakefield near the back of the pump pulse. Test particle simulations indicate that significant amounts of charge can be trapped and accelerated ( approximately 10 pC). For higher charge, beam loading limits the validity of the simulations. The accelerated bunches are ultrashort ( approximately 1 fs) with good beam quality (relative energy spread of a few percent at a mean energy of approximately 10 MeV and a normalized root-mean-square emittance on the order 0.4 mm mrad). The effects of interaction angle and polarization are also explored, e.g., efficient trapping can occur for near-collinear geometries. Beat wave injection using a single injection pulse has the advantages of simplicity, ease of experimental implementation, and requires modest laser intensity < 10(18) W/cm(2).
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Affiliation(s)
- G Fubiani
- Center for Beam Physics, Ernest Orlando Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, USA
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Schroeder CB, Esarey E, Van Tilborg J, Leemans WP. Theory of coherent transition radiation generated at a plasma-vacuum interface. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 69:016501. [PMID: 14995729 DOI: 10.1103/physreve.69.016501] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2003] [Indexed: 05/24/2023]
Abstract
Transition radiation generated by an electron beam, produced by a laser wakefield accelerator operating in the self-modulated regime, crossing the plasma-vacuum boundary is considered. The angular distributions and spectra are calculated for both the incoherent and the coherent radiation. The effects of the longitudinal and transverse momentum distributions on the differential energy spectra are examined. Diffraction radiation from the finite transverse extent of the plasma is considered and shown to strongly modify the spectra and energy radiated for long-wavelength radiation. This method of transition radiation generation has the capability of producing high peak power terahertz radiation, of order 100 microJ/pulse at the plasma-vacuum interface, which is several orders of magnitude beyond current state-of-the-art terahertz sources.
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Affiliation(s)
- C B Schroeder
- Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, USA
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Suk H, Barov N, Rosenzweig JB, Esarey E. Plasma electron trapping and acceleration in a plasma wake field using a density transition. PHYSICAL REVIEW LETTERS 2001; 86:1011-1014. [PMID: 11177997 DOI: 10.1103/physrevlett.86.1011] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2000] [Indexed: 05/23/2023]
Abstract
A new scheme for plasma electron injection into an acceleration phase of a plasma wake field is presented. In this scheme, a single, short electron pulse travels through an underdense plasma with a sharp, localized, downward density transition. Near this transition, a number of background plasma electrons are trapped in the plasma wake field, due to the rapid wavelength increase of the induced wake wave in this region. The viability of this scheme is verified using two-dimensional particle-in-cell simulations. To investigate the trapping and acceleration mechanisms further, a 1D Hamiltonian analysis, as well as 1D simulations, has been performed, with the results presented and compared.
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Affiliation(s)
- H Suk
- Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, California 90095, USA
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