<title>Lifetime survivability of contaminated target-chamber optics</title>

Abstract

November 1996This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. PREPRINTThis paper was prepared for submittal to the DISCLAIMER This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes.Recycled Recyclable ABSTRACTTarget chambers used for Inertial Confinement Fusion (ICF) expose laser optics to a very hostile environment not only from high-fluence laser irradiation but also x-ray irradiation and particulate debris from targets and chamber wall materials. Expendable debris shields provide the first line of defense to more costly optics upstream in the laser beam path to contaminants generated within the target chamber. However, the replacement of a large number of debris shields is also an expensive proposition so that extending their usable lifetime within the chamber is of crucial importance.We have conducted tests to show that optics can both be cleaned and damaged by laser irradiation at 355␣nm after being contaminated with potential chamber-wall materials such as B 4 C and Al 2 O 3 . Such optics can survive from one to hundreds of laser shots depending on the degree of contamination and laser fluence levels. Similarly, we have studied the survivability of optics that have been exposed to direct contamination from representative target materials irradiated in the target chamber. We have also studied the effects on optics that were not directly exposed to targets yet received secondary exposure from the above directly-exposed samples.

A large-aperture high-energy laser system for optics and optical component testing

“…The OSL facility provides such large-beam capabilities. Recently, the existing Optical Laser Sciences facility 1,2,3,4 has been upgraded 5 to provide the capability of handling large (~ 40-cm) optics in a fully integrated environment. Large aperture and integrated testing capabilities are key to providing adequate statistical data for probability studies.…”

Debris mitigation techniques for petawatt-class lasers in high debris environments

“…One way to mitigate this is to maximize the incident angle between laser propagation direction and target normal. However, over time, more and more debris will be collected on the focusing optic which lowers performance and will lead to damage over time [7,8]. For high power lasers, these optics are very expensive and fabrication time can be on the order of years.…”