Contents Return Previous Page Next Page Index


Return To: Session IF - Inertial Fusion Energy (Wednesday, 21
Prev Page: Session IF - Inertial Fusion Energy (Wednesday, 21
Next Page: (IF/5) Progress in Fast Ignitor Research with the

(IF/3) Inertial Confinement Fusion and Fast Ignitor Studies

   
O. Willi , L. Barringer , A. Bell , M. Borghesi , J. Davies , R. Gaillard , A. Iwase , A. Mackinnon , G. Malka , C. Meyer , S. Nuruzzaman , R. Taylor , C. Vickers 
The Blackett Laboratory, Imperial College of Science,Technology and Medicine, London, SW7 2BZ, United Kingdom
 
D. Hoarty 
AWE Aldermaston, Reading, United Kingdom
 
P. Gobby , R. Johnson , R. G. Watt 
Los Alamos National Laboratory, Los Alamos, USA
 
N. Blanchot , B. Canaud , H. Croso , B. Meyer , J. L. Miquel , C. Reverdin 
Commissariat a l'Energie Atomique, Centre d'Etudes de Limeil-Valenton, France
 
A. Pukhov , J. Meyer-Ter Vehn 
Max-Planck-Institut für Quantenoptik, Garching, Germany

Abstract
The paper discusses inertial confinement  fusion research carried out at several different laser facilities including the VULCAN laser  at the Rutherford Appleton Laboratory, the TRIDENT laser  at the Los Alamos National Laboratory and the PHEBUS laser  at Limeil. Low density foam targets  were irradiated either with nanosecond laser or soft x-ray pulses. Laser imprinting was studied and in particular saturation of areal density perturbations induced by near-single mode laser imprinting has been observed. Several issues important for the foam buffered direct drive  scheme were investigated. These studies included measurements of the absolute levels of Stimulated Brillouin and Raman Scattering observed from laser irradiated low density foam targets either bare or overcoated with a thin layer of gold.

A novel scheme is proposed to increase the pressure in indirectly driven targets. Low density foams that are mounted onto a foil target are heated with an intense pulse of soft x-ray radiation. If the foam is heated supersonically the pressure generated is not only the ablation pressure but the combined pressure due to ablation at the foam/foil interface and the heated foam material. The scheme was confirmed on planar targets. Brominated foil targets overcoated with a low density foam were irradiated by a soft x-ray pulse emitted from a hohlraum. The pressure was obtained by comparing the rear side trajectory of the driven target observed by soft x-ray radiography to one dimensional radiation hydrodynamic simulations. Further, measurements were carried out to observe the transition from super- to subsonic propagation of an ionisation front in low density chlorinated foam targets irradiated by an intense soft x-ray pulse both in open and confined geometry. The diagnostic for these measurements was K-shell point projection absorption spectroscopy.

In the fast ignitor  area the channeling and guiding of picosecond laser pulses through underdense plasmas, preformed density channels and microtubes were investigated. It was observed that a large fraction of the incident laser energy can be propagated through preformed channels and microtubes. Magnetic fields in the megagauss range have been measured, with a polarimetric technique, during and after propagation of relativistically intense picosecond pulses on solid targets and preionised plasmas. Two types of toroidal fields, of opposite orientation, generated through different mechanisms, were detected. In addition, the production and propagation of an electron beam through solid glass targets  irradiated at intensities above $\rm 10^{19}
Wcm^{-2}$ was observed using optical probing techniques.

 

Read the full paper in PDF format.


IAEA 1999