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Full-Text Articles in Physics
Observation Of The Plasma Channel Dynamics And Coulomb Explosion In The Interaction Of A High-Intensity Laser Pulse With A He Gas Jet, G.S. Sarkisov, V. Yu. Bychenkov, V.T. Tikhonchuk, Anatoly Maksimchuk, Shouyuan Chen, R. Wagner, G. Mourou, Donald P. Umstadter
Observation Of The Plasma Channel Dynamics And Coulomb Explosion In The Interaction Of A High-Intensity Laser Pulse With A He Gas Jet, G.S. Sarkisov, V. Yu. Bychenkov, V.T. Tikhonchuk, Anatoly Maksimchuk, Shouyuan Chen, R. Wagner, G. Mourou, Donald P. Umstadter
Donald Umstadter Publications
We report the first interferometric observations of the dynamics of electron–ion cavitation of relativistically self-focused intense 4 TW, 400 fs laser pulse in a He gas jet. The electron density in a channel 1 mm long and 30 mm in diameter drops by a factor of approximately 10 from the maximum value of ~8x1019 cm23. A high radial velocity of the plasma expansion, ~3.8x108 cm/s, corresponding to an ion energy of about 300 keV, is observed. The total energy of fast ions is estimated to be 6% of the laser pulse energy. The high-velocity radial plasma …
Observation Of Laser Satellites In A Plasma Produced By A Femtosecond Laser Pulse, S.A. Pikuz, Anatoly Maksimchuk, Donald Umstadter, M. Nantel, I. Yu. Skobelev, A. Ya. Faenov, A. Osterheld
Observation Of Laser Satellites In A Plasma Produced By A Femtosecond Laser Pulse, S.A. Pikuz, Anatoly Maksimchuk, Donald Umstadter, M. Nantel, I. Yu. Skobelev, A. Ya. Faenov, A. Osterheld
Donald Umstadter Publications
Laser satellites are detected in the emission spectra of magnesium and aluminum plasmas produced by femtosecond laser pulses. This is made possible by the realization of picosecond time resolution in a highluminosity x-ray spectrograph with a spherically curved mica crystal. The temporal characteristics of these newly recorded spectral lines show unequivocally that they are formed as a result of nonlinear processes.
“Atomic Processes In High Energy Density Plasmas," Summaries Of Fy 1997 Research In The Chemical Sciences, Donald P. Umstadter
“Atomic Processes In High Energy Density Plasmas," Summaries Of Fy 1997 Research In The Chemical Sciences, Donald P. Umstadter
Donald Umstadter Publications
Several important plasma atomic processes are studied in a controlled manner. These studies are enabled by the recent invention of ultrashortpulse- duration lasers, which produce plasmas with independently controllable parameters.
Study Of Laser Plasma Interactions In The Relativistic Regime, Donald Umstadter
Study Of Laser Plasma Interactions In The Relativistic Regime, Donald Umstadter
Donald Umstadter Publications
We discuss the first experimental demonstration of electron acceleration by a laser wakefield over distances greater than a Rayleigh range (or the distance a laser normally propagates in vacuum). A self-modulated laser wakefield plasma wave is shown to have a field gradient that exceeds that of an RF Iinac by four orders of magnitude (E ≥ 200 GV/m) and accelerates electrons with over l-nC of charge per bunch in a beam with space-charge-limited emittance (1 mm-mrad). Above a laser power threshold, a plasma channel, created by the intense ultrashort laser pulse (I~ 4 x 1018 W/cm2, …
Electron Acceleration By A Laser Wakefield In A Relativistically Self-Guided Channel, R. Wagner, Shouyuan Chen, Anatoly Maksimchuk, Donald P. Umstadter
Electron Acceleration By A Laser Wakefield In A Relativistically Self-Guided Channel, R. Wagner, Shouyuan Chen, Anatoly Maksimchuk, Donald P. Umstadter
Donald Umstadter Publications
Acceleration of electrons to relativistic energies by a multidimensional self-modulated laser wakefield is discussed. Above a power threshold, a relativistically self-guided channel from an intense ultrashort laser pulse (l∼4×1018 W/cm2, λ = 1 μm, τ = 400 fs) was found to increase the laser propagation distance, decrease the electron beam divergence, and increase the energy of the electrons. These electron beam effects occurred even though the propagation distance became significantly longer than the conventional dephasing length.
Application Of A Picosecond Soft X-Ray Source To Time-Resolved Plasma Dynamics, J. Workman, M. Nantel, Anatoly Maksimchuk, Donald P. Umstadter
Application Of A Picosecond Soft X-Ray Source To Time-Resolved Plasma Dynamics, J. Workman, M. Nantel, Anatoly Maksimchuk, Donald P. Umstadter
Donald Umstadter Publications
We demonstrate the application of an ultrashort x-ray source as an external probe to measure plasma dynamics. The plasma is generated by a 100-fs Ti: sapphire laser focused onto thin metallic films. Time-resolved spectroscopy of the gold x-ray probe transmission through a perturbed 1000 Å aluminum film reveals redshifts of the L-shell photoabsorption edge. We show that the dynamic behavior of this shift is consistent with the relaxation of the aluminum following the compression generated by a shock wave traveling through the film. An analytic plasma model, with comparison to a numerical hydrodynamics model, indicates compression up to 1.4 …