Development of z-pinch laser diagnostics at the Zebra generator

The 50 TW Leopard laser coupled with the 1-MA Zebra generator was used for the development of new diagnostics for z-pinch plasmas. Two plasma diagnostics are presented: an x-ray broadband backlighting for z-pinch absorption spectroscopy and parametric two-plasmon decay of the laser beam in dense z-pinch plasma. The implementation of the new diagnostics on the Zebra generator and the first results are discussed. The absorption spectroscopy is based on backlighting the z-pinch plasma with broadband x-ray radiation from the Sm laser plasma. The absorption spectroscopy can deliver data about the electron temperature and density of z-pinch plasma at the non-radiative stage. The parametric two-plasmon decay of intensive laser radiation generates 3/2ω and 1/2ω harmonics. These harmonics can be used to derive the temperature of the z-pinch plasma with the electron density near the quarter of critical plasma density. Ultraviolet (UV) laser probing diagnostics at the wavelength of 266 nm have been developed for the investigation of the 1-MA Z-pinch plasma. The smaller absorption and refraction in dense plasma at the wavelength of 266 nm allows for a deeper penetration into the dense Z-pinch plasma. These features allow for the observation of fine details in the Z-pinch plasma at the implosion and stagnation phases. A shadowgraphy channel with a spatial resolution of 4 μm was tested. An electron density N_e>5·10¹⁹ cm^-3 was measured directly in the stagnated Z-pinch with interferometry at 266 nm. Further development of laser probing diagnostics includes a UV Faraday rotation diagnostic and two-frame UV shadowgraphy. UV laser probing diagnostics give the opportunity to investigate the micro structures and current distribution in the stagnated Z-pinch.