One-dimensional space resolving flat-field holographic grating soft x-ray framing camera spectrograph for laser plasma diagnostics

Abstract

A 1D space resolving x-ray spectrum diagnostic system has been developed to study the radiation opacity of hot plasma on SG-II laser facility. The diagnostic system consists of a 2400 lines/mm flat-field holographic grating and a gated microchannel plate coupled with an optical CCD and covers the wavelength range of 5-50 Å. The holographic grating was compared with a ruled one by measuring the emission spectra from a laser-produced molybdenum plasma. The results indicate that the holographic grating possesses better sensitivity than the ruled grating having nearly similar spectral resolution. The spectrograph has been used in radiative opacity measurement of Fe plasma. Simultaneous measurements of the backlight source and the transmission spectrum in appointed time range in one shot have been accomplished successfully with the holographic grating spectrometer. The 2p-3d transition absorption of Fe plasma near 15.5 Å in has been observed clearly.

Diagnosing the plasma nonuniformity in an iron opacity experiment by spatially resolved Al 1s-2p absorption spectroscopy

“…The spectrometer used to measure the transmission was a gated holographic flat-field grating spectrometer that has relatively low high-order diffraction as described in a previous paper. 24 The spectrometer was able to cover the photon energy range from 200 eV to 1200 eV, with a spectral resolution k/Dk $ 200. The spectra were recorded by a gated microchannel plate (MCP) camera during the 1.4-1.6 ns period after the eight main laser pulses began.…”

Towards an extremely high resolution broad-band flat-field spectrometer in the `water window'

“…In the past few decades, X-ray spectrometers have accomplished rapid development driven by advanced light sources such as synchrotron radiation facilities and free-electron lasers (FELs), and have been widely used for exploring various intriguing research topics especially in the extreme ultraviolet or soft X-ray regimes, e.g. applications of tokamak plasmas and magnetic confinement fusion (Schwob et al, 1987), laserproduced warm dense matter and extreme energy density states (Schwanda et al, 1993), stellar or planetary interior properties (Xiong et al, 2011), instrument development and applications for advanced light sources (Koike et al, 2003). The technique is necessary for providing high spectroscopic resolution in physical, chemical, photonic and biological research.…”

“…Previously, high-resolution spectrometers in this spectral range have included the following designs: grating on Rowland circle structure (Namioka, 1959); single-plane grating grooved in varied line spacing (VLS) (Fan et al, 1992;Xiong et al, 2011); single concave VLS grating (Harada & Kita, 1980;Nakano et al, 1984); concave mirror pre-focusing the incident beam upstream of a plane grating, creating a real secondary source (Choi et al, 1997); beam pre-focused by a spherical mirror to converge beyond the VLS grating, creating a virtual source, i.e. Hettrick-Underwood design (Hettrick et al, 1988), which exists in different versions: e.g.…”

Extreme ultraviolet spectrometer for the Shenguang III laser facility

“…The measurement of EUV x-rays also enables a identification of the bound-bound emission lines from different ion species. Concerning the inertial confinement fusions (ICF) plasmas, a most important application of the EUV spectrum is the measurement of the radiation opacity, which is crucial to energy transport in hightemperature plasmas [17][18][19][20][21][22][23]. The EUV spectrum is important in radiation opacity measurements because the radiative energy flow around the maximum of the Planck distribution lies in this spectral range [17].…”

“…All the spectrometers described above were coupled to a charge-coupled device (CCD) to complete a time integral measurement. In [11], a shutter was placed in front of the entrance slit to provide a time resolution of about 30 ms. As for laser-produced plasmas, the spectrometer often needs to couple with a framing camera or a stream camera to obtain temporal resolution in the picosecond range [4,21]. We have carried out several opacity measurements on iron and gold plasmas at the Shenguang-II (SG-II) laser facility in recent years by using a spectrometer that consists of a 2400 l/mm flat-field grating, an x-ray framing camera, and an imaging slit [21][22][23].…”