The laser architecture of the NIF beamlines requires small- area beam dumps to safely absorb back reflections from the output and leakage through the PEPC switch. The problems presented by these beam dumps are that fluences they must absorb are very large, beyond the damage threshold of any material, and ablation of beam dump materials potentially contaminates adjacent optical components. Full scale tests have demonstrated that a stainless steel beam dump will survive fluence levels and energies as high as 820 J/cm² and 2.5 kJ, respectively. Small scale tests with tungsten, tantalum, and stainless steel have demonstrated erosion rates less than about 0.5 micrometers /shot, with stainless steel having the smallest rate. They also suggest that increased angles of incidence (>= 60 degree(s)) will greatly reduce the material ablated directly back along the beam path.

Date Published: 8 December 1997
PDF: 7 pages
Proc. SPIE 3047, Solid State Lasers for Application to Inertial Confinement Fusion: Second Annual International Conference, (8 December 1997); doi: 10.1117/12.294302

Published in SPIE Proceedings Vol. 3047:
Solid State Lasers for Application to Inertial Confinement Fusion: Second Annual International Conference
Michel L. Andre, Editor(s)