Flash X Radiography of Laser-Accelerated Foils.
Abstract
The successful compression of laser driven pellets to thermonuclear ignition depends on the stability and uniformity of the motion with which dense shells can be imploded. The motion of planar foils accelerated by the Pharos II laser (1.05 micrometers focused to 3 to 6 times 10 to the 12th power W/cm2 in a millimeter diameter spot) has been studied by two-dimensional, flash x-radiography employing pinhole imaging and slitted crystal imaging. The x ray images show that the planar foil targets are accelerated to velocities of 3,000 000 cm/sec with an axial extent as small as 25% of the distance traveled, and maintain a density above 3% of solid. The x radiographic results are in general agreement with two dimensional hydrodynamic simulations and with earlier experimental studies. The attainment of higher velocities, of greater interest to the fusion application, was attempted. The results substantiate the need for improved laser uniformity and hgh speed imaging diagnostics. These crucial issues are being addressed with the upgraded Pharos III laser system with Induced Spatial Incoherence, and are the subject of intensive ongoing investigations whose results are to be published elsewhere. Keywords: Laser accelerated foil; Flash x radiography; Laser plasma; X radiography; X ray backlighting; Laser fusion; Hydrocode; X ray pinhole camera; Density diffractive imaging.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 14, 1986
- Accession Number
- ADA177212
Entities
People
- J. A. Sprague
- Jacob Grün
- John A. Stamper
- R. R. Whitlock
- Stephen P.P. Obenschain
Organizations
- United States Naval Research Laboratory