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Full-Text Articles in Physics
Attosecond Electron Bunch Measurement With Coherent Nonlinear Thomson Scattering, Colton Fruhling, Gregory V. Golovin, Donald Umstadter
Attosecond Electron Bunch Measurement With Coherent Nonlinear Thomson Scattering, Colton Fruhling, Gregory V. Golovin, Donald Umstadter
Donald Umstadter Publications
We present a novel method for measurement of ultrashort electron-bunch duration, in principle, as short as zeptosecond (10−21 s). The method employs nonlinear Thomson scattering of relativistically intense laser light, and takes advantage of the nonlinear dependence and coherence of scattered light on electron bunch length. We validate the method and test its range of applicability via simulations by using realistic (nonideal) electron beams. Due to the wide flexibility in choice of interaction geometry and scattering laser pulse properties enabled by the method, it is shown to be applicable over a wide range of electron beam parameters, including energy, …
Shielded Radiography With A Laser-Driven Mev-Energy X-Ray Source, Shouyuan Chen, Grigory V. Golovin, Cameron Miller, Daniel Haden, Sudeep Banerjee, Ping Zhang, Cheng Liu, Jun Zhang, Baozhen Zhao, Shaun Clarke, Sara Pozzi, Donald Umstadter
Shielded Radiography With A Laser-Driven Mev-Energy X-Ray Source, Shouyuan Chen, Grigory V. Golovin, Cameron Miller, Daniel Haden, Sudeep Banerjee, Ping Zhang, Cheng Liu, Jun Zhang, Baozhen Zhao, Shaun Clarke, Sara Pozzi, Donald Umstadter
Donald Umstadter Publications
We report the results of experimental and numerical-simulation studies of shielded radiography using narrowband MeVenergy X-rays from a compact all-laser-driven inverse-Compton-scattering X-ray light source. This recently developed Xray light source is based on a laser-wakefield accelerator with ultra-high-field gradient (GeV/cm). We demonstrate experimentally high-quality radiographic imaging (image contrast of 0.4 and signal-to-noise ratio of 2:1) of a target composed of 8-mm thick depleted uranium shielded by 80-mm thick steel, using a 6-MeV X-ray beam with a spread of 45% (FWHM) and 107 photons in a single shot. The corresponding dose of the X-ray pulse measured in front of the target …
Control And Optimization Of A Staged Laser-Wakefield Accelerator, Grigory V. Golovin, Sudeep Banerjee, Shouyuan Chen, Nathan D. Powers, Cheng Liu, Wenchao Yan, Jia Zhang, Ping Zhang, Baozhen Zhao, Donald Umstadter
Control And Optimization Of A Staged Laser-Wakefield Accelerator, Grigory V. Golovin, Sudeep Banerjee, Shouyuan Chen, Nathan D. Powers, Cheng Liu, Wenchao Yan, Jia Zhang, Ping Zhang, Baozhen Zhao, Donald Umstadter
Donald Umstadter Publications
We report results of an experimental study of laser-wakefield acceleration of electrons, using a staged device based on a double-jet gas target that enables independent injection and acceleration stages. This novel scheme is shown to produce stable, quasi-monoenergetic, and tunable electron beams. We show that optimal accelerator performance is achieved by systematic variation of five critical parameters. For the injection stage, we show that the amount of trapped charge is controlled by the gas density, composition, and laser power. For the acceleration stage, the gas density and the length of the jet are found to determine the final electron energy. …
Tomographic Imaging Of Nonsymmetric Multicomponent Tailored Supersonic Flows From Structured Gas Nozzles, Grigory V. Golovin, Sudeep Banerjee, J Zhang, Shouyuan Chen, Cheng Liu, Baozhen Zhao, J Mills, Kevin J. Brown, C Petersen, Donald P. Umstadter
Tomographic Imaging Of Nonsymmetric Multicomponent Tailored Supersonic Flows From Structured Gas Nozzles, Grigory V. Golovin, Sudeep Banerjee, J Zhang, Shouyuan Chen, Cheng Liu, Baozhen Zhao, J Mills, Kevin J. Brown, C Petersen, Donald P. Umstadter
Donald Umstadter Publications
We report experimental results on the production and characterization of asymmetric and composite supersonic gas flows, created by merging independently controllable flows from multiple nozzles. We demonstrate that the spatial profiles are adjustable over a large range of parameters, including gas density, density gradient, and atomic composition. The profiles were precisely characterized using three-dimensional tomography. The creation and measurement of complex gas flows is relevant to numerous applications, ranging from laser-produced plasmas to rocket thrusters.
Compact Source Of Narrowband And Tunable X-Rays For Radiography, Sudeep Banerjee, Shouyuan Chen, Nathan D. Powers, Daniel Haden, Cheng Liu, Grigory V. Golovin, Jun Zhang, Baozhen Zhao, S. Clarke, Sara Pozzi, Jack Silano, H. Karwowski, Donald Umstadter
Compact Source Of Narrowband And Tunable X-Rays For Radiography, Sudeep Banerjee, Shouyuan Chen, Nathan D. Powers, Daniel Haden, Cheng Liu, Grigory V. Golovin, Jun Zhang, Baozhen Zhao, S. Clarke, Sara Pozzi, Jack Silano, H. Karwowski, Donald Umstadter
Donald Umstadter Publications
We discuss the development of a compact X-ray source based on inverse-Compton scattering with a laser-driven electron beam. This source produces a beam of high-energy X-rays in a narrow cone angle (5–10 mrad), at a rate of 108 photons-s_1. Tunable operation of the source over a large energy range, with energy spread of ~50%, has also been demonstrated. Photon energies >10 MeV have been obtained. The narrowband nature of the source is advantageous for radiography with low dose, low noise, and minimal shielding.
All-Laser-Driven Thomson X-Ray Sources, Donald Umstadter
All-Laser-Driven Thomson X-Ray Sources, Donald Umstadter
Donald Umstadter Publications
We discuss the development of a new generation of accelerator-based hard X-ray sources driven exclusively by laser light. High-intensity laser pulses serve the dual roles: first, accelerating electrons by laser-driven plasma wakefields, and second, generating X-rays by inverse Compton scattering. Such all-laser-driven X-rays have recently been demonstrated to be energetic, tunable, relatively narrow in bandwidth, short pulsed and well collimated. Such characteristics, especially from a compact source, are highly advantageous for numerous advanced X-ray applications—in metrology, biomedicine, materials, ultrafast phenomena, radiology and fundamental physics.
Tunable Monoenergetic Electron Beams From Independently Controllable Laser-Wakefield Acceleration And Injection, Grigory V. Golovin, Shouyuan Chen, Nathan D. Powers, Cheng Liu, Sudeep Banerjee, J Zhang, M Zeng, Z Sheng, Donald P. Umstadter
Tunable Monoenergetic Electron Beams From Independently Controllable Laser-Wakefield Acceleration And Injection, Grigory V. Golovin, Shouyuan Chen, Nathan D. Powers, Cheng Liu, Sudeep Banerjee, J Zhang, M Zeng, Z Sheng, Donald P. Umstadter
Donald Umstadter Publications
We report the results of experiments on laser-wakefield acceleration in a novel two-stage gas target with independently adjustable density and atomic-composition profiles.We were able to tailor these profiles in a way that led to the separation of the processes of electron injection and acceleration and permitted independent control of both. This resulted in the generation of stable, quasimonoenergetic electron beams with central energy tunable in 50–300 MeV range. For the first time, we are able to independently control the beam charge and energy spread over the entire tunability range.
Wavefront-Correction For Nearly Diffraction Limited Focusing Of Dual-Color Laser Beams To High Intensities, Baozhen Zhao, Jun Zhang, Shouyuan Chen, Cheng Liu, Grigory V. Golovin, Sudeep Banerjee, Kevin J. Brown, Jared Mills, Chad Petersen, Donald Umstadter
Wavefront-Correction For Nearly Diffraction Limited Focusing Of Dual-Color Laser Beams To High Intensities, Baozhen Zhao, Jun Zhang, Shouyuan Chen, Cheng Liu, Grigory V. Golovin, Sudeep Banerjee, Kevin J. Brown, Jared Mills, Chad Petersen, Donald Umstadter
Donald Umstadter Publications
We demonstrate wavefront correction of terawatt-peak-power laser beams at two distinct and well-separated wavelengths. Simultaneous near diffraction-limited focusability is achieved for both the fundamental (800 nm) and second harmonic (400 nm) of Ti:sapphire-amplified laser light. By comparing the relative effectiveness of various correction loops, the optimal ones are found. Simultaneous correction of both beams of different color relies on the linear proportionality between their wavefront aberrations. This method can enable two-color experiments at relativistic intensities.
Generation Of 9 Mev Γ-Rays By All-Laser-Driven Compton Scattering With Second-Harmonic Laser Light, Cheng Liu, Grigory V. Golovin, Shouyuan Chen, Jun Zhang, Baozhen Zhao, Daniel Haden, Sudeep Banerjee, Jack Silano, Hugon Karwowski, Donald Umstadter
Generation Of 9 Mev Γ-Rays By All-Laser-Driven Compton Scattering With Second-Harmonic Laser Light, Cheng Liu, Grigory V. Golovin, Shouyuan Chen, Jun Zhang, Baozhen Zhao, Daniel Haden, Sudeep Banerjee, Jack Silano, Hugon Karwowski, Donald Umstadter
Donald Umstadter Publications
Gamma-ray photons with energy >9 MeV were produced when second-harmonic-generated laser light (3 eV) inverse-Compton-scattered from a counterpropagating relativistic (∼450 MeV) laser-wakefield-accelerated electron beam. Two laser pulses from the same laser system were used: one to accelerate electrons and one to scatter. Since the two pulses play very different roles in the γ-ray generation process, and thus have different requirements, a novel laser system was developed. It separately and independently optimized the optical properties of the two pulses. This approach also mitigated the deleterious effects on beam focusing that generally accompany nonlinear optics at high peak-power levels.
Adaptive-Feedback Spectral-Phase Control For Interactions With Transform-Limited Ultrashort High-Power Laser Pulses, Cheng Liu, Jun Zhang, Shouyuan Chen, Grigory V. Golovin, Sudeep Banerjee, Baozhen Zhao, Nathan D. Powers, Isaac Ghebregziabher, Donald Umstadter
Adaptive-Feedback Spectral-Phase Control For Interactions With Transform-Limited Ultrashort High-Power Laser Pulses, Cheng Liu, Jun Zhang, Shouyuan Chen, Grigory V. Golovin, Sudeep Banerjee, Baozhen Zhao, Nathan D. Powers, Isaac Ghebregziabher, Donald Umstadter
Donald Umstadter Publications
laser in vacuum. The spectral-phase distortion induced by the dispersion mismatching between the stretcher, compressor, and dispersive materials was fully compensated for by means of an adaptive closed-loop. The coherent temporal contrast on the sub-picosecond time scale was two orders of magnitude higher than that without adaptive control. This novel phase control capability enabled the experimental study of the dependence of laser wakefield acceleration on the spectral phase of intense laser light
Improved Particle Statistics For Laser-Plasma Self-Injection Simulations, B W. Cowan, Serguei Y. Kalmykov, Bradley Allan Shadwick, K Bunkers, D L. Bruhwiler, Donald Umstadter
Improved Particle Statistics For Laser-Plasma Self-Injection Simulations, B W. Cowan, Serguei Y. Kalmykov, Bradley Allan Shadwick, K Bunkers, D L. Bruhwiler, Donald Umstadter
Donald Umstadter Publications
We describe methods for improving the accuracy of injected particle beams by selectively enhancing the particle statistics in particle-in-cell simulations, using reduced model computations as a guide. We demonstrate convergence of key beam parameters in two dimensions, and show improved noise properties in three dimensions.
Generation Of Tunable, 100–800 Mev Quasi-Monoenergetic Electron Beams From A Laser-Wakefield Accelerator In The Blowout Regime, Sudeep Banerjee, Nathan D. Powers, Viswanathan Ramanathan, I. Ghebregziabher, Kevin J. Brown, C. Maharjan, Shouyuan Chen, A. Beck, E. Lefebvre, Serguei Y. Kalmykov, Bradley Allan Shadwick, Donald Umstadter
Generation Of Tunable, 100–800 Mev Quasi-Monoenergetic Electron Beams From A Laser-Wakefield Accelerator In The Blowout Regime, Sudeep Banerjee, Nathan D. Powers, Viswanathan Ramanathan, I. Ghebregziabher, Kevin J. Brown, C. Maharjan, Shouyuan Chen, A. Beck, E. Lefebvre, Serguei Y. Kalmykov, Bradley Allan Shadwick, Donald Umstadter
Donald Umstadter Publications
In this paper, we present results on a scalable high-energy electron source based on laser wakefield acceleration. The electron accelerator using 30–80 TW, 30 fs laser pulses, operates in the blowout regime, and produces high-quality, quasi-monoenergetic electron beams in the range 100–800 MeV. These beams have angular divergence of 1–4 mrad, and 5%–25% energy spread, with a resulting brightness 1011 electrons mm-2 MeV-1 mrad-2. The beam parameters can be tuned by varying the laser and plasma conditions. The use of a high-quality laser pulse and appropriate target conditions enables optimization of beam quality, concentrating a …
Laser-Wakefield Accelerators: Glass-Guiding Benefits, Donald P. Umstadter
Laser-Wakefield Accelerators: Glass-Guiding Benefits, Donald P. Umstadter
Donald Umstadter Publications
A main attraction of laser-driven electron accelerators is their absence of cavity walls, which can break down in the presence of intense electric fields. Now it seems that the inclusion of a hollow glass fibre cavity could lead to more efficient acceleration at lower laser intensities. ... Further research will reveal which of the above methods for guiding light will ultimately prove best for future accelerator designs. In any case, although it is perhaps ironic that the relatively old technology of glass waveguides may benefit next-generation accelerators, it is nonetheless satisfying to see such a classic photonic solution come to …
Background-Free, Quasi-Monoenergetic Electron Beams From A Self-Injected Laser Wakefield Accelerator, Sudeep Banerjee, Serguei Y. Kalmykov, Nathan D. Powers, Viswanathan Ramanathan, Nathan A. Chandler-Smith, Kevin J. Brown, Shuo Chen, A. Moorthi, I. Ghebregziabher, C. Maharjan, Bradley Allan Shadwick, Donald Umstadter, A. Beck, E. Lefebvre, A. Cowan, D. Bruhwiler
Background-Free, Quasi-Monoenergetic Electron Beams From A Self-Injected Laser Wakefield Accelerator, Sudeep Banerjee, Serguei Y. Kalmykov, Nathan D. Powers, Viswanathan Ramanathan, Nathan A. Chandler-Smith, Kevin J. Brown, Shuo Chen, A. Moorthi, I. Ghebregziabher, C. Maharjan, Bradley Allan Shadwick, Donald Umstadter, A. Beck, E. Lefebvre, A. Cowan, D. Bruhwiler
Donald Umstadter Publications
Stable 200–400-MeV quasi-monoenergetic electron bunches (ΔE/Eno dark-currentare produced when a self-injected laser plasma accelerator is optimized. PIC simulations demonstrate these beams are produced near the threshold for selfinjection.
Electron Self-Injection Into An Evolving Plasma Bubble: Quasi-Monoenergetic Laser-Plasma Acceleration In The Blowout Regime, Serguei Y. Kalmykov, A. Beck, S. A. Yi, V. N. Khudik, Michael C. Downer, E. Lefebvre, Bradley Allan Shadwick, Donald Umstadter
Electron Self-Injection Into An Evolving Plasma Bubble: Quasi-Monoenergetic Laser-Plasma Acceleration In The Blowout Regime, Serguei Y. Kalmykov, A. Beck, S. A. Yi, V. N. Khudik, Michael C. Downer, E. Lefebvre, Bradley Allan Shadwick, Donald Umstadter
Donald Umstadter Publications
An electron density bubble driven in a rarefied uniform plasma by a slowly evolving laser pulse goes through periods of adiabatically slow expansions and contractions. Bubble expansion causes robust self-injection of initially quiescent plasma electrons, whereas stabilization and contraction terminate self-injection thus limiting injected charge; concomitant phase space rotation reduces the bunch energy spread. In regimes relevant to experiments with hundred terawatt- to petawatt-class lasers, bubble dynamics and, hence, the self-injection process are governed primarily by the driver evolution. Collective transverse fields of the trapped electron bunch reduce the accelerating gradient and slow down phase space rotation. Bubble expansion followed …
Submillimeter-Resolution Radiography Of Shielded Structures With Laser-Accelerated Electron Beams, Viswanathan Ramanathan, Sudeep Banerjee, Nathan D. Powers, Nathaniel Cunningham, Nathan A. Chandler-Smith, Kun Zhao, Kevin J. Brown, Donald Umstadter, Shaun Clarke, Sara Pozzi, James Beene, Randy Vane, David Schultz
Submillimeter-Resolution Radiography Of Shielded Structures With Laser-Accelerated Electron Beams, Viswanathan Ramanathan, Sudeep Banerjee, Nathan D. Powers, Nathaniel Cunningham, Nathan A. Chandler-Smith, Kun Zhao, Kevin J. Brown, Donald Umstadter, Shaun Clarke, Sara Pozzi, James Beene, Randy Vane, David Schultz
Donald Umstadter Publications
We investigate the use of energetic electron beams for high-resolution radiography of flaws embedded in thick solid objects. A bright, monoenergetic electron beam (with energy >100 MeV) was generated by the process of laser-wakefield acceleration through the interaction of 50-TW, 30-fs laser pulses with a supersonic helium jet. The high energy, low divergence, and small source size of these beams make them ideal for high-resolution radiographic studies of cracks or voids embedded in dense materials that are placed at a large distance from the source. We report radiographic imaging of steel with submillimeter resolution.
High-Energy Laser-Accelerated Electron Beans For Long-Range Interrogation, Nathaniel Cunningham, Sudeep Banerjee, Viswanathan Ramanathan, Nathan D. Powers, Nathan A. Chandler-Smith, Randy Vane, David Schultz, Sara Pozzi, Shaun Clark, James Beene, Donald Umstadter
High-Energy Laser-Accelerated Electron Beans For Long-Range Interrogation, Nathaniel Cunningham, Sudeep Banerjee, Viswanathan Ramanathan, Nathan D. Powers, Nathan A. Chandler-Smith, Randy Vane, David Schultz, Sara Pozzi, Shaun Clark, James Beene, Donald Umstadter
Donald Umstadter Publications
We are studying the use of 0.1 - 1.0 GeV laser-accelerated electron beams as active interrogation probes for long-standoff radiography or nuclear activation of concealed special nuclear material. Use of beams in this energy range is largely unexplored, but such beams could provide notable advantages over lower-energy beams and x-rays. High-energy laser-accelerated electrons exhibit large penetration range through air and solids, and low beam divergence for both direct beams and secondary Bremsstrahlung x-rays. We present laboratory measurements of radiography and activation using the high power Diocles laser system at the University of Nebraska, as well as MCNP and GEANT Monte …
Development Of A Source Of Quasi-Monochromatic Mev Energy Photons, Donald Umstadter, Sudeep Banerjee, Viswanathan Ramanathan, Nathan D. Powers, Nathaniel Cunningham, Nathan A. Chandler-Smith
Development Of A Source Of Quasi-Monochromatic Mev Energy Photons, Donald Umstadter, Sudeep Banerjee, Viswanathan Ramanathan, Nathan D. Powers, Nathaniel Cunningham, Nathan A. Chandler-Smith
Donald Umstadter Publications
We report current progress on a project to develop an all-optically-driven x-ray photon source. A laser pulse with 40-50 TW of peak power is focused on a supersonic helium nozzle to drive a relativistic plasma wave. Electron beams with energies of 320 MeV (+/- 28 MeV) are accelerated by means of laser wakefield acceleration. Remarkably, the acceleration region is only 3 mm in length. This accelerator is currently being employed to demonstrate the generation of MeV- energy x-ray by means of all-optical Thomson scattering. By this mechanism, a lower power, laser pulse (from the same laser system) is focused onto …
Experimental Observation Of Nonlinear Thomson Scattering, Szu-Yuan Chen, Anatoly Maksimchuk, Donald Umstadter
Experimental Observation Of Nonlinear Thomson Scattering, Szu-Yuan Chen, Anatoly Maksimchuk, Donald Umstadter
Donald Umstadter Publications
A century ago, J. J. Thomson showed that the scattering of low-intensity light by electrons was a linear process (i.e., the scattered light frequency was identical to that of the incident light) and that light’s magnetic field played no role. To- day, with the recent invention of ultra-high-peak- power lasers it is now possible to create a sufficient photon density to study Thomson scattering in the relativistic regime. With increasing light intensity, electrons quiver during the scattering process with increasing velocity, approaching the speed of light when the laser intensity approaches 1018 W/cm2. In this limit, the …
Observation Of Relativistic Cross-Phase Modulation In High-Intensity Laser-Plasma Interactions, Shouyuan Chen, Matthew Rever, P. Zhang, W. Theobald, Donald Umstadter
Observation Of Relativistic Cross-Phase Modulation In High-Intensity Laser-Plasma Interactions, Shouyuan Chen, Matthew Rever, P. Zhang, W. Theobald, Donald Umstadter
Donald Umstadter Publications
A nonlinear optical phenomenon, relativistic cross-phase modulation, is reported. A relativistically intense light beam (I=1.3×1018 W cm-2, λ =1.05 μm) is experimentally observed to cause phase modulation of a lower intensity, copropagating light beam in a plasma. The latter beam is generated when the former undergoes the stimulated Raman forward scattering instability. The bandwidth of the Raman satellite is found to be broadened from 3.8–100 nm when the pump laser power is increased from 0.45–2.4 TW. A signature of relativistic cross-phase modulation, namely, asymmetric spectral broadening of the Raman signal, is observed at a pump …
Exact Analytical Solution For The Vector Electromagnetic Field Of Gaussian, Flattened Gaussian, And Annular Gaussian Laser Modes, Scott M. Sepke, Donald Umstadter
Exact Analytical Solution For The Vector Electromagnetic Field Of Gaussian, Flattened Gaussian, And Annular Gaussian Laser Modes, Scott M. Sepke, Donald Umstadter
Donald Umstadter Publications
The exact vector integral solution for all the electromagnetic field components of a general flattened Gaussian laser mode is derived by using the angular spectrum method. This solution includes the pure and annular Gaussian modes as special cases. The integrals are of the form of Gegenbauer’s finite integral and are computed analytically for each case, yielding fields satisfying the Maxwell equations exactly in the form of quickly converging Fourier–Gegenbauer series.
Analytical Solutions For The Electromagnetic Fields Of Tightly Focused Laser Beams Of Arbitrary Pulse Length, Scott M. Sepke, Donald Umstadter
Analytical Solutions For The Electromagnetic Fields Of Tightly Focused Laser Beams Of Arbitrary Pulse Length, Scott M. Sepke, Donald Umstadter
Donald Umstadter Publications
The analytical solution for a monochromatic focused laser beam was recently published [Opt. Lett. 31, 1447 (2006)]. The effect of introducing bandwidth by including a finite-length temporal pulse envelope is included exactly. This is done formally first in the frequency domain for an arbitrary pulse shape, and the specific case of a cosine-squared envelope is then solved analytically for all pulse lengths, thereby decreasing the computation time by 2 orders of magnitude. The inclusion of longer wavelengths reduces the fraction of laser energy in the focus from 86.5% to 83.5% for a 5 fs Ti:sapphire laser and 72.7% in a …
Thomson Scattering And Ponderomotive Intermodulation Within Standing Laser Beat Waves In Plasma, Scott Sepke, Y.Y. Lau, James Paul Holloway, Donald P. Umstadter
Thomson Scattering And Ponderomotive Intermodulation Within Standing Laser Beat Waves In Plasma, Scott Sepke, Y.Y. Lau, James Paul Holloway, Donald P. Umstadter
Donald Umstadter Publications
Electrons in a standing electromagnetic wave—an optical lattice—tend to oscillate due to the quiver and ponderomotive potentials. For sufficiently intense laser fields (lλ2≤5×1017 W cm-2 µm2) and in plasmas with sufficiently low electron densities (n≤1018 cm-3), these oscillations can occur faster than the plasma can respond. This paper shows that these oscillations result in Thomson scattering of light at both the laser and ponderomotive bounce frequencies and their harmonics as well as at mixtures of these frequencies. We term this mixing ponderomotive intermodulation. Here, the case of counterpropagating …
Optical Deflection And Temporal Characterization Of An Ultrafast Laser-Produced Electron Beam, Sudeep Banerjee, Scott Sepke, Rahul Shah, Anthony Valenzuela, Anatoly Maksimchuk, Donald P. Umstadter
Optical Deflection And Temporal Characterization Of An Ultrafast Laser-Produced Electron Beam, Sudeep Banerjee, Scott Sepke, Rahul Shah, Anthony Valenzuela, Anatoly Maksimchuk, Donald P. Umstadter
Donald Umstadter Publications
The interaction of a laser-produced electron beam with an ultraintense laser pulse in free space is studied. We show that the optical pulse with a0=0.5 imparts momentum to the electron beam, causing it to deflect along the laser propagation direction. The observed 3-degree angular deflection is found to be independent of polarization and in good agreement with a theoretical model for the interaction of free electrons with a tightly focused Gaussian pulse, but only when longitudinal fields are taken into account. This technique is used to temporally characterize a subpicosecond laser-wakefield-driven electron bunch. Applications to electron-beam conditioning are …
Laser Based Synchrotron Radiation, Kim Ta Phuoc, Frederic Burgy, Jean-Philippe Rousseau, Victor Malka, Antoine Rousse, Rahul Shah, Donald P. Umstadter, Alexander Puhkov, Sergei Kiselev
Laser Based Synchrotron Radiation, Kim Ta Phuoc, Frederic Burgy, Jean-Philippe Rousseau, Victor Malka, Antoine Rousse, Rahul Shah, Donald P. Umstadter, Alexander Puhkov, Sergei Kiselev
Donald Umstadter Publications
Beams of x rays in the kiloelectronvolt energy range have been produced from laser-matter interaction. Here, energetic electrons are accelerated by a laser wakefield, and experience betatron oscillations in an ion channel formed in the wake of the intense femtosecond laser pulse. Experiments using a 50 TW laser (30 fs duration) are described, as well as comparisons with numerical simulations. These results pave the way of a new generation of radiation in the x-ray spectral range, with a high collimation and an ultrafast pulse duration, produced by the use of compact laser system.
Einstein’S Impact On Optics At The Frontier, Donald Umstadter
Einstein’S Impact On Optics At The Frontier, Donald Umstadter
Donald Umstadter Publications
The seminal contributions made by Einstein a century ago have enabled a new frontier area of science, called high-field science. This research involves the physics of the interactions of matter with electromagnetic fields at its highest levels ever achieved in the laboratory. Besides being of fundamental importance to physics research, the discoveries being made in this area are also leading to a new generation of compact and ultrashort-duration particle accelerators and X-ray light sources, with applications ranging from nuclear fusion to cancer therapy.
Simulation Of Ultrashort Electron Pulse Generation From Optical Injection Into Wake-Field Plasma Waves, D.S. Dodd, J.K. Kim, Donald P. Umstadter
Simulation Of Ultrashort Electron Pulse Generation From Optical Injection Into Wake-Field Plasma Waves, D.S. Dodd, J.K. Kim, Donald P. Umstadter
Donald Umstadter Publications
A laser-plasma-based source of relativistic electrons is described in detail, and analyzed in two dimensions using theoretical and numeric techniques. Two laser beams are focused in a plasma, one exciting a wake-field electron plasma wave while another locally alters some electron trajectories in such a way that they can be trapped and accelerated by the wave. Previous analyses dealt only with one-dimensional models. In this paper two-dimensional particle-in-cell simulations and analysis of single particle trajectories show that the radial wake field plays an important role. The simulation results are interpreted to evaluate the accelerated electron beam's properties and compared with …
Mechanism And Control Of High-Intensity-Laser-Driven Proton Acceleration, T. Lin, K. Flippo, M. Rever, Anatoly Maksimchuk, Donald P. Umstadter
Mechanism And Control Of High-Intensity-Laser-Driven Proton Acceleration, T. Lin, K. Flippo, M. Rever, Anatoly Maksimchuk, Donald P. Umstadter
Donald Umstadter Publications
We discuss the optimization and control of laser-driven proton beams. Specifically, we report on the dependence of high-intensity laser accelerated proton beams on the material properties of various thin-film targets. Evidence of star-like filaments and beam hollowing (predicted from the electrothermal instability theory) is observed on Radiochromic Film (RCF) and CR-39 nuclear track detectors. The proton beam spatial profile is found to depend on initial target conductivity and target thickness. For resistive target materials, these structured profiles are explained by the inhibition of current, due to the lack of a return current. The conductors, however, can support large propagating currents …
Production Of A Kev X-Ray Beam From Synchrotron Radiation In Relativistic Laser-Plasma Interaction, Antoine Rousse, Kim Ta Phuoc, Rahul Shah, Alexander Pukhov, Eric Lefebvre, Victor Malka, Sergey Kiselev, Frederic Burgy, Jean-Philippe Rousseau, Donald P. Umstadter, Daniele Hulin
Production Of A Kev X-Ray Beam From Synchrotron Radiation In Relativistic Laser-Plasma Interaction, Antoine Rousse, Kim Ta Phuoc, Rahul Shah, Alexander Pukhov, Eric Lefebvre, Victor Malka, Sergey Kiselev, Frederic Burgy, Jean-Philippe Rousseau, Donald P. Umstadter, Daniele Hulin
Donald Umstadter Publications
We demonstrate that a beam of x-ray radiation can be generated by simply focusing a single high-intensity laser pulse into a gas jet. A millimeter-scale laser-produced plasma creates, accelerates, and wiggles an ultrashort and relativistic electron bunch. As they propagate in the ion channel produced in the wake of the laser pulse, the accelerated electrons undergo betatron oscillations, generating a femtosecond pulse of synchrotron radiation, which has keV energy and lies within a narrow (50 mrad) cone angle.
High-Energy Ion Generation By Short Laser Pulses, Anatoly Maksimchuk, K. Flippo, H. Krause, G. Mourou, K. Nemoto, D. Schultz, Donald P. Umstadter, R. Vane, V. Yu. Bychenkov, G.I. Dudnikova, V.F. Kovalev, K. Mima, V.N. Novikov, Y. Sentoku, S.V. Tolokonnikov
High-Energy Ion Generation By Short Laser Pulses, Anatoly Maksimchuk, K. Flippo, H. Krause, G. Mourou, K. Nemoto, D. Schultz, Donald P. Umstadter, R. Vane, V. Yu. Bychenkov, G.I. Dudnikova, V.F. Kovalev, K. Mima, V.N. Novikov, Y. Sentoku, S.V. Tolokonnikov
Donald Umstadter Publications
This paper reviews the many recent advances at the Center for Ultrafast Optical Science (CUOS) at the University of Michigan in multi-MeV ion beam generation from the interaction of short laser pulses focused onto thin foil targets at intensities ranging from 1017 to 1019 W/cm2. Ion beam characteristics were studied by changing the laser intensity, laser wavelength, target material, and by depositing a well-absorbed coating. We manipulated the proton beam divergence using shaped targets and observed nuclear transformation induced by high-energy protons and deuterons. Qualitative theoretical approaches and fully relativistic two-dimensional particle-in-cell simulations modeled energetic ion …