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Full-Text Articles in Physics
Temporal Characterization Of A Self-Modulated Laser Wakefield, S.P. Le Blanc, M.C. Downer, R. Wagner, Shouyuan Chen, Anatoly Maksimchuk, G. Mourou, Donald P. Umstadter
Temporal Characterization Of A Self-Modulated Laser Wakefield, S.P. Le Blanc, M.C. Downer, R. Wagner, Shouyuan Chen, Anatoly Maksimchuk, G. Mourou, Donald P. Umstadter
Donald Umstadter Publications
The temporal envelope of plasma density oscillations in the wake of an intense (l∼4×1018 W/cm2, λ = 1 μm) laser pulse (400 fs) is measured using forward Thomson scattering from a copropagating, frequency-doubled probe pulse. The wakefield oscillations in a fully ionized helium plasma (ne = 3×1019 cm-3) are observed to reach maximum amplitude ( δne/ne∼0.1) 300 fs after the pump pulse. The wakefield growth ( 3.5 ps-1) and decay ( 1.9 ps-1) rates are consistent with the forward Raman …
Laser Injection Of Ultrashort Electron Pulses Into Wakefield Plasma Waves, Donald P. Umstadter, J.K. Kim, E. Dodd
Laser Injection Of Ultrashort Electron Pulses Into Wakefield Plasma Waves, Donald P. Umstadter, J.K. Kim, E. Dodd
Donald Umstadter Publications
A novel laser-plasma-based source of relativistic electrons is described. It involves a combination of orthogonally directed laser beams, which are focused in a plasma. One beam excites a wakefield electron plasma wave. Another locally alters the trajectory of some of the electrons in such a way that they can be accelerated and trapped by the wave. With currently available table-top terawatt lasers, a single ultrashort-duration electron bunch can be accelerated to multi-MeV energies in a fraction of a millimeter, with femtosecond synchronization between the light pulse, the electron bunch, and the plasma wave. Both analytical and numerical-simulation results are presented.
Signal Averaging X-Ray Streak Camera With Picosecond Jitter, Anatoly Maksimchuk, M. Kim, J. Workman, G. Korn, J. Squier, D. Du, Donald Umstadter, G. Mourou, M. Bouvier
Signal Averaging X-Ray Streak Camera With Picosecond Jitter, Anatoly Maksimchuk, M. Kim, J. Workman, G. Korn, J. Squier, D. Du, Donald Umstadter, G. Mourou, M. Bouvier
Donald Umstadter Publications
We have developed an averaging picosecond x-ray streak camera using a dc-biased photoconductive switch as a generator of a high-voltage ramp. The streak camera is operated at a sweep speed of up to 8 ps/mm, shot-to-shot jitter is less than ±1 ps. The streak camera has been used to measure the time history of broadband x-ray emission from an ultrashort pulse laser-produced plasma. Accumulation of the streaked x-ray signals significantly improved the signal-to-noise ratio of the data obtained.
Tabletop Laser Accelerators Are On The Way, Phillip F. Schewe, Ben Stein, Donald P. Umstadter
Tabletop Laser Accelerators Are On The Way, Phillip F. Schewe, Ben Stein, Donald P. Umstadter
Donald Umstadter Publications
The goal here is to use high electric fields in plasmas to accelerate electrons to 100-GeV energies over distances of meters rather than kilometers. This should promote the development of new particle colliders and x-ray sources. The predicted high acceleration gradients in plasmas have been achieved in recent years, but could only be used with external electron injection from a conventional source. Now scientists at the University of Michigan (Donald Umstadter, 313-764-2284) have made progress in eliminating conventional electron sources altogether. In a preliminary experiment, by simply focusing a laser into a plasma, the Michigan scientists have extracted a collimated …