Debris from High-Aspect-Ratio Rectangular Focused Laser Irradiation on a Tape Target Surface in an X-Ray Laser System

• Published in: Japanese Journal of Applied Physics 1998-09, Vol.37 (9R), p.5071
• Main Authors: Hisada, Yoshiyuki, Abraha, Petros, Takamoto, Kiichi, Yamaguchi, Naohiro, Hara, Tamio
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.37.5071

This study measures the distribution of debris ejected from an aluminum tape target subjected to laser irradiation. The irradiation area is rectangular with a high aspect ratio of 67. The power density of the laser beam is 8×10 10 W/cm 2 at the irradiation surface. The ejected debris is collected on a plane parallel to the target surface. The angular distribution of debris thickness in the direction parallel to the longer side of the irradiation area is cos 60 θ h . Similarly, the angular distribution of debris thickness in the direction parallel to the shorter side of the irradiation area is cos 5 θ v , where the angles θ h and θ v are deviations from the irradiation surface normal in the horizontal and vertical directions, respectively. An additional feature is the sacrificial film feed mechanism designed to shield the laser beam entrance window from debris deposition. Based on the angular distribution of debris thickness, the film feed rate is adjusted to ensure delivery of the required beam energy at the target surface.