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Donald Umstadter Publications

1985

Articles 1 - 2 of 2

Full-Text Articles in Physics

Clayton Et Al. Respond, C.E. Clayton, C. Joshi, C. Darrow, Donald P. Umstadter Oct 1985

Clayton Et Al. Respond, C.E. Clayton, C. Joshi, C. Darrow, Donald P. Umstadter

Donald Umstadter Publications

Clayton et al. Respond: The authors of the Comment are quite correct when they point out that the ruby-laser scattering system used in our study can only respond to beat-excited density fluctuations with ky = k2, where the CO2 (ruby) beam propagates in the z (y) direction.


Relativistic Plasma-Wave Excitation By Collinear Optical Mixing, C.E. Clayton, C. Joshi, C. Darrow, Donald P. Umstadter May 1985

Relativistic Plasma-Wave Excitation By Collinear Optical Mixing, C.E. Clayton, C. Joshi, C. Darrow, Donald P. Umstadter

Donald Umstadter Publications

The relativistic plasma wave excited when the frequency difference between two copropagating CO2 laser beams equals the plasma frequency is detected for the first time. The plasma-wave frequency, wave number, spatial extent, and saturation time are directly measured by use of 7-mrad, collective, ruby Thomson scattering and the forward-scattered ir spectrum. The wave amplitude /n0 is inferred to be (1-3)% which gives a longitudinal electric field of 0.3 to 1 GV/m at a laser intensity of 1.7×1013 W/cm2, in reasonable agreement with theory.