Csaba Toth | Lawrence Berkeley National Laboratory (original) (raw)

Papers by Csaba Toth

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 17, 2011

Experimental results are reported from two measurement techniques ͑semiconductor switching and el... more Experimental results are reported from two measurement techniques ͑semiconductor switching and electro-optic sampling͒ that allow temporal characterization of electron bunches produced by a laser-driven plasma-based accelerator. As femtosecond electron bunches exit the plasma-vacuum interface, coherent transition radiation ͑at THz frequencies͒ is emitted. Measuring the properties of this radiation allows characterization of the electron bunches. Theoretical work on the emission mechanism is presented, including a model that calculates the THz wave form from a given bunch profile. It is found that the spectrum of the THz pulse is coherent up to the 200 m thick crystal ͑ZnTe͒ detection limit of 4 THz, which corresponds to the production of sub-50 fs ͑rms͒ electron bunch structure. The measurements demonstrate both the shot-to-shot stability of bunch parameters that are critical to THz emission ͑such as total charge and bunch length͒, as well as femtosecond synchronization among bunch, THz pulse, and laser beam.

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 17, 2011

The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laser-... more The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laser-wakefieldaccelerated electron bunches, are studied. The near-single-cycle THz pulses are measured with two singleshot techniques in the temporal and spatial domains. Spectra of 0-6 THz and peak fields up to Ӎ0.4 MV cm −1 are observed. The measured field substructure demonstrates the manifestation of spatiotemporal coupling at focus, which affects the interpretation of THz radiation as a bunch diagnostic and in highfield pump-probe experiments.

A nonlinear optical pulse cleaning technique based on cross-polarized wave (XPW) generation filte... more A nonlinear optical pulse cleaning technique based on cross-polarized wave (XPW) generation filtering [1] has been implemented to improve laser pulse contrast, and consequently to control pre-ionization in laser-plasma accelerator experiments. Three orders of magnitude improvement in pre-pulse contrast has been achieved, resulting in 4-fold increase in electron charge and improved stability of both the electron beam energy and THz radiation generated as a secondary process in the gas-jet-based LWFA experiments.

Optics Letters, 2008

We present a new approach (demonstrated experimentally and through modeling) to characterize the ... more We present a new approach (demonstrated experimentally and through modeling) to characterize the spectral envelope of a terahertz (THz) pulse in a single shot. The coherent THz pulse is produced by a femtosecond electron bunch and contains information on the bunch duration. The technique, involving a single lowpower laser probe pulse, is an extension of the conventional spectral encoding method (limited in time resolution to hundreds of femtoseconds) into a regime only limited in resolution by the laser pulse length (tens of femtoseconds). While only the bunch duration is retrieved (and not the exact charge profile), such a measurement provides a useful and critical parameter for optimization of the electron accelerator.

2007 IEEE Particle Accelerator Conference (PAC), 2007

At LBNL, laser wakefield accelerators (LWFA) can now produce ultra-short electron bunches with en... more At LBNL, laser wakefield accelerators (LWFA) can now produce ultra-short electron bunches with energies up to 1 GeV [1]. As femtosecond electron bunches exit the plasma they radiate an intense burst in the terahertz range [2,3] via coherent transition radiation (CTR). Measuring the CTR properties allows non-invasive bunchlength diagnostics [4], a key to continuing rapid advance in LWFA technology. Experimental bunch length characterization for two different energy regimes through bolometric analysis and electro-optic (EO) sampling are presented. Measurements demonstrate both shot-to-shot stability of bunch parameters, and femtosecond synchronization between the bunch, the THz pulse, and the laser beam. In addition, this method of CTR generation provides THz pulses of very high peak power suitable for applications. Recent results reveal LWFA to be a promising intense ultrafast THz source.

AIP Conference Proceedings, 2009

ABSTRACT The LOASIS Laser Wakefield Accelerator (LWFA) has achieved quasi-mono-energetic electron... more ABSTRACT The LOASIS Laser Wakefield Accelerator (LWFA) has achieved quasi-mono-energetic electron beams with energies up to 1 GeV. These beams offer the potential for use with insertion devices such as wigglers and undulators to create tabletop XUV and x-ray free-electron laser (FEL) sources. To achieve a high quality light source producing high brightness radiation requires an electron beam with low energy spread and low emittance. Here we discuss the use of an undulator to generate XUV radiation to characterize in a single shot the electron beam energy spread and emittance with high precision.

Bulletin of the American …, 2005

Index Babzien Canova Chowdhury Chvykov Corner Ditmire Donovan Flippo Galvanauskas Gaul Karsch Kru... more Index Babzien Canova Chowdhury Chvykov Corner Ditmire Donovan Flippo Galvanauskas Gaul Karsch Krushelnick Leemans Lu Martinez Osterhoff Polyanskiy Rosenzweig Roth Schroeder Specka Toth Umstadter Zeil Name of submitting author Mr. Marcus Babzien Institution Brookhaven National Laboratory Email babzien@bnl.gov Abstract Title BNL ATF Timing System Upgrades Author/Affiliation listing M. Babzien, M. Montemagno, V. Yakimenko Brookhaven National Laboratory, Upton NY 11973Title BNL ATF Timing System Upgrades Author/Affiliation listing M. Babzien, M. Montemagno, V. Yakimenko Brookhaven National Laboratory, Upton NY 11973 Abstract A key enabling technology in advanced accelerators is the synchronization of precision frequency and pulse sources at the picosecond or subpicosecond level. The synchronization system employed at the BNL Accelerator Test Facility will be presented, as well as ongoing work to extend present capabilities to multiple laser and RF sources.A key enabling technology in ad...

AIP Conference Proceedings, 2009

Ultrashort terahertz pulses with energies in the µJ range can be generated with laser wakefield a... more Ultrashort terahertz pulses with energies in the µJ range can be generated with laser wakefield accelerators (LWFA), which are novel, compact accelerators that produce ultrashort electron bunches with energies up to 1 GeV [1] and energy spreads of a few-percent. Laser pulses interacting with a plasma create accelerated electrons which upon exiting the plasma emit terahertz pulses via transition radiation. Because these electron bunches are ultrashort (< 50 fs), they can radiate coherently (coherent transition radiation-CTR) in a wide bandwidth (1-10 THz) yielding high intensity terahertz pulses [2]. In addition to providing a non-invasive bunch-length ∼ diagnostic [3] and thus feedback for the LWFA, these high peak power THz pulses are suitable for high field (MV/cm) pump-probe experiments. Here we present energy-based measurements using a Golay cell and an electro-optic technique which were used to characterize these THz pulses.

AIP Conference Proceedings, 2009

Laser wakefield acceleration experiments were carried out by using a hydrogen-filled capillary di... more Laser wakefield acceleration experiments were carried out by using a hydrogen-filled capillary discharge waveguide. For a 15 mm long, 200 µm diameter capillary, quasi-monoenergetic e-beams up to 300 MeV were observed. By de-tuning discharge delay from optimum guiding performance, self-trapping was found to be stabilized. For a 33 mm long, 300 µm capillary, a parameter regime with high energy electron beams, up to 1 GeV, was found. In this regime, the electron beam peak energy was correlated with the amount of trapped electrons.

AIP Conference Proceedings, 2002

We have conducted particle-in-cell simulations of laser pulse propagation through neutral He, inc... more We have conducted particle-in-cell simulations of laser pulse propagation through neutral He, including the effects of tunneling ionization, within the parameter regime of the l'OASIS experiments [1, 2] at the Lawrence Berkeley National Lab (LBNL). The simulations show the theoretically predicted [3] blue shifting of the laser frequency at the leading edge of the pulse. The observed blue shifting is in good agreement with the experimental data. These results indicate that such computations can be used to accurately simulate a number of important effects related to tunneling ionization for laser-plasma accelerator concepts, such as steepening due to ionization-induced pump depletion, which can seed and enhance instabilities. Our simulations show self-modulation occurring earlier when tunneling ionization is included then for a pre-ionized plasma.

AIP Conference Proceedings, 2004

The Lasers, Optical Accelerator Systems Integrated Studies (L'OASIS) Lab of LBNL operates a highl... more The Lasers, Optical Accelerator Systems Integrated Studies (L'OASIS) Lab of LBNL operates a highly automated and remotely controlled Ti:sapphire chirped pulse amplification (CPA) laser system that provides synchronized beams of 2x1.0 TW, 12 TW, and 100 TW peakpower, in a unique, radiation shielded facility. The system has been specially designed for studying high field laser-plasma interactions and particularly aimed for the investigations of laser wake-field particle acceleration. It generates and recombines multiple beams having different pulse durations, wavelengths, and pulse energies for various stages of plasma preparation, excitation, and diagnostics. The amplifier system is characterized and continuously monitored via local area network (LAN) from a radiation shielded control room by an array of diagnostics, including beam profile monitoring cameras, remote controlled alignment options, self-correcting beam-pointing stabilization loops, pulse measurement tools, such as single-shot autocorrelator for pulse duration and third-order correlator for contrast measurements, FROG for pulse shape studies.

Springer Series in Chemical Physics, 2001

Using time-resolved x-ray diffraction the ultafast strain dynamics in fslaserexcited Ge/Si-hetero... more Using time-resolved x-ray diffraction the ultafast strain dynamics in fslaserexcited Ge/Si-heterostructures has been studied. A fluence dependent, anharmonic damping of the impulsively generated acoustic phonons and vibrational transport across the buried Ge/Si-interface are observed.

We present spatiotemporal characterization of yuJ-class ultrashort THz pulses generated from a la... more We present spatiotemporal characterization of yuJ-class ultrashort THz pulses generated from a laser wakefield accelerator (LWFA). Accelerated electrons [1], resulting from the interaction of a high-intensity laser pulse with a plasma, emit high-intensity THz pulses as coherent transition radiation [2]. Such high peak-power THz pulses, suitable for high-field (MV/cm) pump-probe experiments [3], also provide a non-invasive bunch-length diagnostic [4] and thus feedback for the accelerator. The characterization of the THz pulses includes energy measurement using a Golay cell, 2D sign-resolved electro-optic measurement and single-shot spatiotemporal electric-field distribution retrieval using a new technique, coined temporal electric-field cross-Correlation (TEX). All three techniques corroborate THz pulses of ~ 5 /J, with peak fields of 100's of kV/cm and ~ 0.4 ps rms duration.

Optics Letters, 2007

The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laserw... more The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laserwakefield-accelerated electron bunches, are studied. The near-single-cycle THz pulses are measured with two single-shot techniques in the temporal and spatial domains. Spectra of 0 − 6 THz and peak fields up to 0.4 MV cm −1 are observed. The measured field substructure demonstrates the manifestation of spatio-temporal coupling at focus, which affects the interpretation of THz radiation as a bunch diagnostic and in high-field pump-probe experiments. A ray-based model confirms the coupling.

IEEE Transactions on Plasma Science, 2005

Electron beam based radiation sources provide electromagnetic radiation for countless application... more Electron beam based radiation sources provide electromagnetic radiation for countless applications. The properties of the radiation are primarily determined by the properties of the electron beam. Compact laser driven accelerators are being developed that can provide ultra-short electron bunches (femtosecond duration) with relativistic energies reaching towards a GeV. The electron bunches are produced when an intense laser interacts with a dense plasma and excites a large amplitude plasma density modulation (wakefield) that can trap background electrons and accelerate them to high energies. The short pulse nature of the accelerated bunches and high particle energy offer the possibility of generating radiation from one compact source that ranges from coherent terahertz to gamma rays. The intrinsic synchronization to a laser pulse and unique character of the radiation offers a wide range of possibilities for scientific applications. Two particular radiation source regimes are discussed: coherent terahertz emission and x-ray emission based on betatron oscillations and Thomson scattering.

Proceedings of the 2005 Particle Accelerator Conference

A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with ... more A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with low emittance and energy spread by extending the interaction length using a plasma channel. Wakefield accelerators support gradients thousands of times those achievable in RF accelerators, but short acceleration distance, limited by diffraction, has resulted in low energy beams with 100% electron energy spread. In the present experiments on the L'OASIS laser, the relativistically intense drive pulse was guided over 10 diffraction ranges by a plasma channel. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing >200pC charge above 80 MeV and with normalized emittance estimated at < 2 π-mm-mrad were produced. Data and simulations (VORPAL code) show the high quality bunch was formed when beam loading turned off injection after initial trapping, and when the particles were extracted as they dephased from the wake. Up to 4TW was guided without trapping, potentially providing a platform for controlled injection. The plasma channel technique forms the basis of a new class of accelerators, with high gradients and high beam quality.

Author(s): Geddes, Cameron; Matlis, Nicholas; Steinke, Sven; Esarey, Eric; Mittelberger, Daniel; ... more Author(s): Geddes, Cameron; Matlis, Nicholas; Steinke, Sven; Esarey, Eric; Mittelberger, Daniel; Rykovanov, Sergey; Schroeder, Carl; Toth, Csaba; Nakamura, Kei; Vay, Jean-Luc; Ludewigt, Bernhard; Quiter, Brian; Barton, Paul; Zhang, Yigong; Vetter, Kai; Leemans, Wim

IEEE Journal of Quantum Electronics, 2017

AIP Conference Proceedings, 2004

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 17, 2011

Experimental results are reported from two measurement techniques ͑semiconductor switching and el... more Experimental results are reported from two measurement techniques ͑semiconductor switching and electro-optic sampling͒ that allow temporal characterization of electron bunches produced by a laser-driven plasma-based accelerator. As femtosecond electron bunches exit the plasma-vacuum interface, coherent transition radiation ͑at THz frequencies͒ is emitted. Measuring the properties of this radiation allows characterization of the electron bunches. Theoretical work on the emission mechanism is presented, including a model that calculates the THz wave form from a given bunch profile. It is found that the spectrum of the THz pulse is coherent up to the 200 m thick crystal ͑ZnTe͒ detection limit of 4 THz, which corresponds to the production of sub-50 fs ͑rms͒ electron bunch structure. The measurements demonstrate both the shot-to-shot stability of bunch parameters that are critical to THz emission ͑such as total charge and bunch length͒, as well as femtosecond synchronization among bunch, THz pulse, and laser beam.

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 17, 2011

The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laser-... more The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laser-wakefieldaccelerated electron bunches, are studied. The near-single-cycle THz pulses are measured with two singleshot techniques in the temporal and spatial domains. Spectra of 0-6 THz and peak fields up to Ӎ0.4 MV cm −1 are observed. The measured field substructure demonstrates the manifestation of spatiotemporal coupling at focus, which affects the interpretation of THz radiation as a bunch diagnostic and in highfield pump-probe experiments.

A nonlinear optical pulse cleaning technique based on cross-polarized wave (XPW) generation filte... more A nonlinear optical pulse cleaning technique based on cross-polarized wave (XPW) generation filtering [1] has been implemented to improve laser pulse contrast, and consequently to control pre-ionization in laser-plasma accelerator experiments. Three orders of magnitude improvement in pre-pulse contrast has been achieved, resulting in 4-fold increase in electron charge and improved stability of both the electron beam energy and THz radiation generated as a secondary process in the gas-jet-based LWFA experiments.

Optics Letters, 2008

We present a new approach (demonstrated experimentally and through modeling) to characterize the ... more We present a new approach (demonstrated experimentally and through modeling) to characterize the spectral envelope of a terahertz (THz) pulse in a single shot. The coherent THz pulse is produced by a femtosecond electron bunch and contains information on the bunch duration. The technique, involving a single lowpower laser probe pulse, is an extension of the conventional spectral encoding method (limited in time resolution to hundreds of femtoseconds) into a regime only limited in resolution by the laser pulse length (tens of femtoseconds). While only the bunch duration is retrieved (and not the exact charge profile), such a measurement provides a useful and critical parameter for optimization of the electron accelerator.

2007 IEEE Particle Accelerator Conference (PAC), 2007

At LBNL, laser wakefield accelerators (LWFA) can now produce ultra-short electron bunches with en... more At LBNL, laser wakefield accelerators (LWFA) can now produce ultra-short electron bunches with energies up to 1 GeV [1]. As femtosecond electron bunches exit the plasma they radiate an intense burst in the terahertz range [2,3] via coherent transition radiation (CTR). Measuring the CTR properties allows non-invasive bunchlength diagnostics [4], a key to continuing rapid advance in LWFA technology. Experimental bunch length characterization for two different energy regimes through bolometric analysis and electro-optic (EO) sampling are presented. Measurements demonstrate both shot-to-shot stability of bunch parameters, and femtosecond synchronization between the bunch, the THz pulse, and the laser beam. In addition, this method of CTR generation provides THz pulses of very high peak power suitable for applications. Recent results reveal LWFA to be a promising intense ultrafast THz source.

AIP Conference Proceedings, 2009

ABSTRACT The LOASIS Laser Wakefield Accelerator (LWFA) has achieved quasi-mono-energetic electron... more ABSTRACT The LOASIS Laser Wakefield Accelerator (LWFA) has achieved quasi-mono-energetic electron beams with energies up to 1 GeV. These beams offer the potential for use with insertion devices such as wigglers and undulators to create tabletop XUV and x-ray free-electron laser (FEL) sources. To achieve a high quality light source producing high brightness radiation requires an electron beam with low energy spread and low emittance. Here we discuss the use of an undulator to generate XUV radiation to characterize in a single shot the electron beam energy spread and emittance with high precision.

Bulletin of the American …, 2005

Index Babzien Canova Chowdhury Chvykov Corner Ditmire Donovan Flippo Galvanauskas Gaul Karsch Kru... more Index Babzien Canova Chowdhury Chvykov Corner Ditmire Donovan Flippo Galvanauskas Gaul Karsch Krushelnick Leemans Lu Martinez Osterhoff Polyanskiy Rosenzweig Roth Schroeder Specka Toth Umstadter Zeil Name of submitting author Mr. Marcus Babzien Institution Brookhaven National Laboratory Email babzien@bnl.gov Abstract Title BNL ATF Timing System Upgrades Author/Affiliation listing M. Babzien, M. Montemagno, V. Yakimenko Brookhaven National Laboratory, Upton NY 11973Title BNL ATF Timing System Upgrades Author/Affiliation listing M. Babzien, M. Montemagno, V. Yakimenko Brookhaven National Laboratory, Upton NY 11973 Abstract A key enabling technology in advanced accelerators is the synchronization of precision frequency and pulse sources at the picosecond or subpicosecond level. The synchronization system employed at the BNL Accelerator Test Facility will be presented, as well as ongoing work to extend present capabilities to multiple laser and RF sources.A key enabling technology in ad...

AIP Conference Proceedings, 2009

Ultrashort terahertz pulses with energies in the µJ range can be generated with laser wakefield a... more Ultrashort terahertz pulses with energies in the µJ range can be generated with laser wakefield accelerators (LWFA), which are novel, compact accelerators that produce ultrashort electron bunches with energies up to 1 GeV [1] and energy spreads of a few-percent. Laser pulses interacting with a plasma create accelerated electrons which upon exiting the plasma emit terahertz pulses via transition radiation. Because these electron bunches are ultrashort (< 50 fs), they can radiate coherently (coherent transition radiation-CTR) in a wide bandwidth (1-10 THz) yielding high intensity terahertz pulses [2]. In addition to providing a non-invasive bunch-length ∼ diagnostic [3] and thus feedback for the LWFA, these high peak power THz pulses are suitable for high field (MV/cm) pump-probe experiments. Here we present energy-based measurements using a Golay cell and an electro-optic technique which were used to characterize these THz pulses.

AIP Conference Proceedings, 2009

Laser wakefield acceleration experiments were carried out by using a hydrogen-filled capillary di... more Laser wakefield acceleration experiments were carried out by using a hydrogen-filled capillary discharge waveguide. For a 15 mm long, 200 µm diameter capillary, quasi-monoenergetic e-beams up to 300 MeV were observed. By de-tuning discharge delay from optimum guiding performance, self-trapping was found to be stabilized. For a 33 mm long, 300 µm capillary, a parameter regime with high energy electron beams, up to 1 GeV, was found. In this regime, the electron beam peak energy was correlated with the amount of trapped electrons.

AIP Conference Proceedings, 2002

We have conducted particle-in-cell simulations of laser pulse propagation through neutral He, inc... more We have conducted particle-in-cell simulations of laser pulse propagation through neutral He, including the effects of tunneling ionization, within the parameter regime of the l'OASIS experiments [1, 2] at the Lawrence Berkeley National Lab (LBNL). The simulations show the theoretically predicted [3] blue shifting of the laser frequency at the leading edge of the pulse. The observed blue shifting is in good agreement with the experimental data. These results indicate that such computations can be used to accurately simulate a number of important effects related to tunneling ionization for laser-plasma accelerator concepts, such as steepening due to ionization-induced pump depletion, which can seed and enhance instabilities. Our simulations show self-modulation occurring earlier when tunneling ionization is included then for a pre-ionized plasma.

AIP Conference Proceedings, 2004

The Lasers, Optical Accelerator Systems Integrated Studies (L'OASIS) Lab of LBNL operates a highl... more The Lasers, Optical Accelerator Systems Integrated Studies (L'OASIS) Lab of LBNL operates a highly automated and remotely controlled Ti:sapphire chirped pulse amplification (CPA) laser system that provides synchronized beams of 2x1.0 TW, 12 TW, and 100 TW peakpower, in a unique, radiation shielded facility. The system has been specially designed for studying high field laser-plasma interactions and particularly aimed for the investigations of laser wake-field particle acceleration. It generates and recombines multiple beams having different pulse durations, wavelengths, and pulse energies for various stages of plasma preparation, excitation, and diagnostics. The amplifier system is characterized and continuously monitored via local area network (LAN) from a radiation shielded control room by an array of diagnostics, including beam profile monitoring cameras, remote controlled alignment options, self-correcting beam-pointing stabilization loops, pulse measurement tools, such as single-shot autocorrelator for pulse duration and third-order correlator for contrast measurements, FROG for pulse shape studies.

Springer Series in Chemical Physics, 2001

Using time-resolved x-ray diffraction the ultafast strain dynamics in fslaserexcited Ge/Si-hetero... more Using time-resolved x-ray diffraction the ultafast strain dynamics in fslaserexcited Ge/Si-heterostructures has been studied. A fluence dependent, anharmonic damping of the impulsively generated acoustic phonons and vibrational transport across the buried Ge/Si-interface are observed.

We present spatiotemporal characterization of yuJ-class ultrashort THz pulses generated from a la... more We present spatiotemporal characterization of yuJ-class ultrashort THz pulses generated from a laser wakefield accelerator (LWFA). Accelerated electrons [1], resulting from the interaction of a high-intensity laser pulse with a plasma, emit high-intensity THz pulses as coherent transition radiation [2]. Such high peak-power THz pulses, suitable for high-field (MV/cm) pump-probe experiments [3], also provide a non-invasive bunch-length diagnostic [4] and thus feedback for the accelerator. The characterization of the THz pulses includes energy measurement using a Golay cell, 2D sign-resolved electro-optic measurement and single-shot spatiotemporal electric-field distribution retrieval using a new technique, coined temporal electric-field cross-Correlation (TEX). All three techniques corroborate THz pulses of ~ 5 /J, with peak fields of 100's of kV/cm and ~ 0.4 ps rms duration.

Optics Letters, 2007

The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laserw... more The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laserwakefield-accelerated electron bunches, are studied. The near-single-cycle THz pulses are measured with two single-shot techniques in the temporal and spatial domains. Spectra of 0 − 6 THz and peak fields up to 0.4 MV cm −1 are observed. The measured field substructure demonstrates the manifestation of spatio-temporal coupling at focus, which affects the interpretation of THz radiation as a bunch diagnostic and in high-field pump-probe experiments. A ray-based model confirms the coupling.

IEEE Transactions on Plasma Science, 2005

Electron beam based radiation sources provide electromagnetic radiation for countless application... more Electron beam based radiation sources provide electromagnetic radiation for countless applications. The properties of the radiation are primarily determined by the properties of the electron beam. Compact laser driven accelerators are being developed that can provide ultra-short electron bunches (femtosecond duration) with relativistic energies reaching towards a GeV. The electron bunches are produced when an intense laser interacts with a dense plasma and excites a large amplitude plasma density modulation (wakefield) that can trap background electrons and accelerate them to high energies. The short pulse nature of the accelerated bunches and high particle energy offer the possibility of generating radiation from one compact source that ranges from coherent terahertz to gamma rays. The intrinsic synchronization to a laser pulse and unique character of the radiation offers a wide range of possibilities for scientific applications. Two particular radiation source regimes are discussed: coherent terahertz emission and x-ray emission based on betatron oscillations and Thomson scattering.

Proceedings of the 2005 Particle Accelerator Conference

A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with ... more A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with low emittance and energy spread by extending the interaction length using a plasma channel. Wakefield accelerators support gradients thousands of times those achievable in RF accelerators, but short acceleration distance, limited by diffraction, has resulted in low energy beams with 100% electron energy spread. In the present experiments on the L'OASIS laser, the relativistically intense drive pulse was guided over 10 diffraction ranges by a plasma channel. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing >200pC charge above 80 MeV and with normalized emittance estimated at < 2 π-mm-mrad were produced. Data and simulations (VORPAL code) show the high quality bunch was formed when beam loading turned off injection after initial trapping, and when the particles were extracted as they dephased from the wake. Up to 4TW was guided without trapping, potentially providing a platform for controlled injection. The plasma channel technique forms the basis of a new class of accelerators, with high gradients and high beam quality.

Author(s): Geddes, Cameron; Matlis, Nicholas; Steinke, Sven; Esarey, Eric; Mittelberger, Daniel; ... more Author(s): Geddes, Cameron; Matlis, Nicholas; Steinke, Sven; Esarey, Eric; Mittelberger, Daniel; Rykovanov, Sergey; Schroeder, Carl; Toth, Csaba; Nakamura, Kei; Vay, Jean-Luc; Ludewigt, Bernhard; Quiter, Brian; Barton, Paul; Zhang, Yigong; Vetter, Kai; Leemans, Wim

IEEE Journal of Quantum Electronics, 2017

AIP Conference Proceedings, 2004