Relativistic spherical plasma waves

Tightly focused laser pulses as they diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we report on theoretical study of relativistic spherical wake waves and their properties, including wave breaking. These waves may be suitable as particle injectors or as flying mirrors that both reflect and focus radiation, enabling unique X-ray sources and nonlinear QED phenomena.Comment: 6 pages; 4 figure

Harmonic Generation by an Intense Laser Pulse in Neutral and Ionized Gases

Reported are the results of a harmonic generation experiment in a simple gas (hydrogen) using 1-ps, 1-pm laser pulses with a range of intensities extending from below to far above the laser ionization saturation threshold. The scaling with intensity above saturation of the third harmonic generated by a single laser-pulse in a filled gas cell is observed to not fit with a simple model that takes into consideration volume ionization effects alone. In another experiment, a pump-probe type, an upper limit on the conversion efficiency of third harmonic generation in a preformed plasma is determined. It is found to be in agreement with the efficiency predicted by a relativistic harmonic generation theory

First Post-War Geologic Field Conference April 25, 26, and 27, 1947

The conference is planned to provide an opportunity to observe and discuss the outcrop sections of the Silurian and Devonian rocks in southeastern Indiana. The broad aspects of the stratigraphy and fauna will be emphasized since most persons attending will not be intimately familiar with these formations

On the Theory of Relativistic Strong Plasma Waves

The influence of motion of ions and electron temperature on nonlinear one-dimensional plasma waves with velocity close to the speed of light in vacuum is investigated. It is shown that although the wavebreaking field weakly depends on mass of ions, the nonlinear relativistic wavelength essentially changes. The nonlinearity leads to the increase of the strong plasma wavelength, while the motion of ions leads to the decrease of the wavelength. Both hydrodynamic approach and kinetic one, based on Vlasov-Poisson equations, are used to investigate the relativistic strong plasma waves in a warm plasma. The existence of relativistic solitons in a thermal plasma is predicted.Comment: 13 pages, 8 figure

Upper and Middle Mississippian Formations of Southern Indiana

Indiana Geological Survey Guidebook 2This field trip was organized to observe and discuss outcrop of Upper and Middle Mississippian age in Indiana. These formations are of special economic interest because the greater part of petroleum, agricultural limestone, road metal, and building stone in Indiana is produced from this rock series. The stratigraphy of the Indiana Chester formations is emphasized because of the wide divergence of opinion held upon their correlation with the subsurface formations of the Illinois Basin and the outcrops of similar age in the states surrounding the basin. The problems of time correlation by fossil evidence and of lithologic correlation by sedimentation units will be discussed. We hope that discussion combined with actual field examples of the Indiana section will provide a better understanding of the Chester correlation problems to all conference members. This opportunity to become better acquainted and to exchange ideas is the most important part of the program.Department of Geology, Indiana University; Indiana Division of Geology; Indiana Department of Conservatio

Stratigraphy Along Mississippian-Pennsylvanian Unconformity of Western Indiana

Indiana Geological Survey Guidebook 4The Mississippian-Pennsylvanian unconformity is the most pronounced and extensive break in the Paleozoic rocks of the Eastern Interior Basin. During the long erosional interval Mississippian beds were truncated and a topographic surface of considerable relief was developed. Pennsylvanian sediments rest on Upper Chester beds in southwestern Indiana, on Meremacian limestones in midwestern Indiana and on Osagian and upper Devonian beds in northwestern Indiana. Outcrops selected for the 1950 Field Conference show the Mississippian-Pennsylvanian unconformity and the stratigraphy along the unconformity in midwestern Indiana. Basal Pennsylvanian beds will be seen resting on Lower Chester, Ste. Genevieve, St. Louis, Salem, Harrodsburg, and Borden rocks representing a truncation approximately 260 feet of sediments. This conference was planned to observe and discuss problems associated with a portion of the Mississippian-Pennsylvanian unconformity. Mississippian stratigraphy will be emphasized, and special attention will be given to the old Mississippian topography and to the lithology of the basal Pennsylvanian beds. We hope that discussion combined with actual field observation will be of mutual benefit.Department of Geology, Indiana University; Indiana Division of Geology; Indiana Department of Conservatio

Silurian and Devonian Formations in Southeastern Indiana

Indiana Geological Survey Guidebook 1This conference was planned to provide an opportunity to observe and discuss outcrops of Silurian and Devonian rocks in southeastern Indiana. The broad aspects of the stratigraphy and fauna were emphasized since most persons attending were not familiar with these formations. It was hoped the discussions would help solve many problems concerning these rocks. Any assistance that can be provided in the subsurface identification and correlation of the counterparts of these formations in the surrounding basin areas will help make the conference a success. Campbell's (1942) recent reclassification of the Devonian will be especially interesting to those familiar with the older classification and terminology. The opportunity to become acquainted and discuss mutual problems was an important part of the program.Department of Geology, Indiana University; Indiana Division of Geology; Indiana Department of Conservatio

Laser-heater assisted plasma channel formation in capillary discharge waveguides

A method of creating plasma channels with controllable depth and transverse profile for the guiding of short, high power laser pulses for efficient electron acceleration is proposed. The plasma channel produced by the hydrogen-filled capillary discharge waveguide is modified by a ns-scale laser pulse, which heats the electrons near the capillary axis. This interaction creates a deeper plasma channel within the capillary discharge that evolves on a ns-time scale, allowing laser beams with smaller spot sizes than would otherwise be possible in the unmodified capillary discharge.Comment: 5 pages, 3 figure

Laser acceleration of ion beams

We consider methods of charged particle acceleration by means of high-intensity lasers. As an application we discuss a laser booster for heavy ion beams provided, e.g. by the Dubna nuclotron. Simple estimates show that a cascade of crossed laser beams would be necessary to provide additional acceleration to gold ions of the order of GeV/nucleon.Comment: 4 pages, 4 figures, Talk at the Helmholtz International Summer School "Dense Matter in heavy Ion Collisions and Astrophysics", August 21 - September 1, 2006, JINR Dubna, Russia; v2, misprints correcte

The reflectivity of relativistic ultra-thin electron layers

The coherent reflectivity of a dense, relativistic, ultra-thin electron layer is derived analytically for an obliquely incident probe beam. Results are obtained by two-fold Lorentz transformation. For the analytical treatment, a plane uniform electron layer is considered. All electrons move with uniform velocity under an angle to the normal direction of the plane; such electron motion corresponds to laser acceleration by direct action of the laser fields, as it is described in a companion paper. Electron density is chosen high enough to ensure that many electrons reside in a volume \lambda_R^3, where \lambda_R is the wavelength of the reflected light in the rest frame of the layer. Under these conditions, the probe light is back-scattered coherently and is directed close to the layer normal rather than the direction of electron velocity. An important consequence is that the Doppler shift is governed by \gamma_x=(1-(V_x/c)^2)^{-1/2} derived from the electron velocity component V_x in normal direction rather than the full \gamma-factor of the layer electrons.Comment: 7 pages, 4 figures, submitted to the special issue "Fundamental Physics with Ultra-High Fields" in The European Physical Journal