Laser-assisted vacuum arc extreme ultraviolet source: a comparison of picosecond and nanosecond laser triggering. (4th May 2016)

• Record Type: Journal Article
• Authors: Beyene, Girum A; Tobin, Isaac; Juschkin, Larissa; Hayden, Patrick; O'Sullivan, Gerry; Sokell, Emma; Zakharov, Vassily S; Zakharov, Sergey V; O'Reilly, Fergal
• Is Part Of: Journal of physics. Volume 49:Number 22(2016)
• Publication Date: 2016-05-04
• Subjects: extreme ultraviolet radiation -- laser-assisted discharge -- tin-plasma -- conversion efficiency -- ps-triggering; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/49/22/225201
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Extreme ultraviolet (EUV) light generation by hybrid laser-assisted vacuum arc discharge plasmas, utilizing Sn-coated rotating-disc-electrodes, was investigated. The discharge was initiated by localized ablation of the liquid tin coating of the cathode disc by a laser pulse. The laser pulse, at 1064 nm, was generated by Nd:YAG lasers with variable energy from 1 to 100 mJ per pulse. The impact of shortening the laser pulse from 7 ns to 170 ps on the EUV generation has been investigated in detail. The use of ps pulses resulted in an increase in emission of EUV radiation. With a fixed discharge energy of ~4 J, the EUV conversion efficiency tends to plateau at ~2.4 ± 0.25% for the ps laser pulses, while for the ns pulses, it saturates at ~1.7 ± 0.3%. Under similar discharge and laser energy conditions, operating the EUV source with the ps-triggering resulted also in narrower spectral profiles of the emission in comparison to ns-triggering. The results indicate an advantage in using ps-triggering in laser-assisted discharges to produce brighter plasmas required for applications such as metrology.