Recent advances in development and application of laser plasma x-ray sources based on a gas puff target (Conference Presentation)

Abstract

Laser plasma sources of soft X-rays and extreme ultraviolet (EUV) have been developed for application in various fields of science and technology. The sources are based on a gas puff target irradiated with a nanosecond laser pulse. The targets are created using an electromagnetic valve system equipped with a double-nozzle. The valve system, which is supplied with two different gases, produces a double-stream gas puff target which consists of an elongated stream of high-Z gas surrounded by a stream of low-Z gas. The double-stream gas puff target approach secures high conversion efficiency of laser energy into soft X-ray and EUV energy without degradation of the nozzle. The targets are irradiated with laser pulses produced by commercial Nd:YAG lasers (EKSPLA) with a duration of 1 ns to 10 ns, energy in the pulse from 0.5 J to 10 J with a repetition of 10 Hz. The sources have been applied in various fields, including metrology, processing of materials, nanoimaging, radiography and tomography, photoionized plasma studies, and radiobiology. In this paper the recent results on application of the sources in X-ray absorption spectroscopy and optical coherence tomography (OCT) are presented. The use of the source in laboratory systems for the near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is demonstrated. The NEXAFS system was applied for 2-D elemental mapping of EUV-modified polymer samples. A single-shot exposure NEXAFS spectroscopy is presented. Application of the source in X-ray optical coherence tomography (XCT) has been also demonstrated. The preliminary results on XCT imaging of Mo/Si multilayers with 2 nm axial resolution, using broad-band soft X-ray emission, are presented.