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The design and first results of a high‐transmission soft X‐ray spectrometer operated at the X‐SPEC double‐undulator beamline of the KIT Light Source are presented. As a unique feature, particular emphasis was placed on optimizing the spectrometer transmission by maximizing the solid angle and the efficiencies of spectrometer gratings and detector. A CMOS detector, optimized for soft X‐rays, allows for quantum efficiencies of 90% or above over the full energy range of the spectrometer, while simultaneously offering short readout times. Combining an optimized control system at the X‐SPEC beamline with continuous energy scans (as opposed to step scans), the high transmission of the spectrometer, and the fast readout of the CMOS camera, enable the collection of entire rapid resonant inelastic soft X‐ray scattering maps in less than 1 min. Series of spectra at a fixed energy can be taken with a frequency of up to 5 Hz. Furthermore, the use of higher‐order reflections allows a very wide energy range (45 to 2000 eV) to be covered with only two blazed gratings, while keeping the efficiency high and the resolving power E/ΔE above 1500 and 3000 with low‐ and high‐energy gratings, respectively. [ABSTRACT FROM AUTHOR]

The design and first results of a high-transmission soft X-ray spectrometer operated at the X-SPEC double-undulator beamline of the KIT Light Source are presented. As a unique feature, particular emphasis was placed on optimizing the spectrometer transmission by maximizing the solid angle and the efficiencies of spectrometer gratings and detector. A CMOS detector, optimized for soft X-rays, allows for quantum efficiencies of 90% or above over the full energy range of the spectrometer, while simultaneously offering short readout times. Combining an optimized control system at the X-SPEC beamline with continuous energy scans (as opposed to step scans), the high transmission of the spectrometer, and the fast readout of the CMOS camera, enable the collection of entire rapid resonant inelastic soft X-ray scattering maps in less than 1 min. Series of spectra at a fixed energy can be taken with a frequency of up to 5 Hz. Furthermore, the use of higher-order reflections allows a very wide energy range (45 to 2000 eV) to be covered with only two blazed gratings, while keeping the efficiency high and the resolving power E/ΔE above 1500 and 3000 with low- and high-energy gratings, respectively.

The optical design of a Hettrick-Underwood-style soft X-ray spectrometer with Wolter type 1 mirrors is presented. The spectrometer with a nominal length of 3.1 m can achieve a high resolving power (resolving power higher than 10000) in the soft X-ray regime when a small source beam (

The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a sounding rocket instrument that flew on July 30, 2021 from the White Sands Missile Range, NM. The instrument was designed to address specific science questions that require differential emission measures of the solar soft X-ray spectrum from 6 – 25 Å(0.5 – 2.1 keV). MaGIXS comprises a Wolter-I telescope, a slit-jaw imaging system, an identical pair of grazing incidence paraboloid mirrors, a planar grating and a CCD camera. While implementing this design, some limitations were encountered in the production of the X-ray mirrors, which ended up as a catalyst for the development of a deterministic polishing approach and an improved meteorological technique that utilizes a computer-generated hologram (CGH). The opto-mechanical design approach addressed the need to have adjustable and highly repeatable interfaces to allow for the complex alignment between the optical sub-assemblies. The alignment techniques employed when mounting the mirrors and throughout instrument integration and end-to-end testing are discussed. Also presented are spatial resolution measurements of the end-to-end point-spread-function that were obtained during testing in the X-ray Cryogenic Facility (XRCF) at NASA Marshall Space Flight Center. Lastly, unresolved issues and off-nominal performance are discussed. [ABSTRACT FROM AUTHOR]

The design and main characteristics of the Wide Energy range Spectrometer at TIMEX (WEST) operating at the FERMI Free Electron Laser are described. WEST covers the entire photon energy range of the FERMI source including its fundamental emission (extreme ultraviolet region, EUV) and its highest harmonics (soft X-ray region) spanning about a thousand of electrovolts from 20 to 1000 eV. The instrument is specifically designed to measure FERMI FEL spectra with good resolving power (500 < R P < 7000) and provide remarkable signal to noise ratio adequate for single-shot experiments. Notably, WEST is aligned in transmission geometry downstream of the TIMEX experimental beamline thus offering a valid diagnostic tool for the characterization of both linear and nonlinear spectral effects driven by the interaction between FEL radiation and samples in gaseous, liquid and solid phase. Detailed theoretical analysis of the instrument performance complemented by experimental measurements is presented. Further possible upgrades of WEST are finally considered and discussed. [ABSTRACT FROM AUTHOR]

Abstract A flat-field soft X-ray spectrometer operating in the spectral range of 250–1240 eV was designed and built for warm dense matter and high-energy density plasma physics. It employs a grazing incidence toroidal mirror as a focusing optic, an aberration-corrected varied line-spacing concave grating with 2400 lines/mm as a dispersive element, and a charge coupled device as an X-ray detector. The dispersion and energy resolution are calibrated with a high-power laser-produced plasma and X-ray free electron laser sources. A resolving power over 370 was achieved over the entire spectral range. A super broadband spectrum in the range of 250–1000 eV was measured from the laser-produced bismuth plasma. The signal-to-noise ratio of 130 was obtained with an average of 10 pulses. These results demonstrate the capability of the spectrometer for single laser shot based experiments for warm dense matter and high energy density plasma research. Highlights • A state-of-art soft X-ray spectrometer for warm dense matter research is developed. • Super broadband soft X-ray spectrum is measured from the laser-produced plasma. • Spectral resolution and signal-to-noise ratio demonstrate a capability of the spectrograph for single-shot based warm dense matter and high energy density plasma research. [ABSTRACT FROM AUTHOR]

In the experiment of inertial confinement fusion, soft X-ray spectrum unfolding can provide important information to optimize the design of the laser and target. As the laser beams increase, there are limited locations for installing detection channels to obtain measurements, and the soft X-ray spectrum can be difficult to recover. In this paper, a novel recovery method of soft X-ray spectrum unfolding based on compressive sensing is proposed, in which (1) the spectrum recovery is formulated as a problem of accurate signal recovery from very few measurements (i.e., compressive sensing), and (2) the proper basis atoms are selected adaptively over a Legendre orthogonal basis dictionary with a large size and Lasso regression in the sense of ℓ1 norm, which enables the spectrum to be accurately recovered with little measured data from the limited detection channels. Finally, the presented approach is validated with experimental data. The results show that it can still achieve comparable accuracy from only 8 spectrometer detection channels as it has previously done from 14 detection channels. This means that the presented approach is capable of recovering spectrum from the data of limited detection channels, and it can be used to save more space for other detectors.

Highlights: [•] A soft X-ray spectrometer was successfully developed on EAST tokamak. [•] The system can observe impurity line emissions with good spectral resolution. [•] Typical line emission measurements from the EAST tokamak were illustrated. [Copyright &y& Elsevier]

Etched multilayers obtained by forming a laminar grating pattern within interferential multilayer mirrors are used in the soft X-ray range to improve the spectral resolution of wavelength dispersive spectrometers equipped with periodic multilayers. We describe the fabrication process of such an etched multilayer dispersive element, its characterization through reflectivity measurement and simulations, and its implementation in a high-resolution Johann-type spectrometer. The specially designed patterning of a Mo/B4C multilayer is found fruitful in the range of the C K emission as the diffraction pattern narrows by a factor 4 with respect to the non-etched structure. This dispersive element with an improved spectral resolution was successfully implemented for electronic structure study with an improved spectral resolution by X-ray emission spectroscopy. As first results, we present the distinction between the chemical states of carbon atoms in various compounds, such as graphite, SiC and B4C, by the different shape of their C K emission band. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the experiment of inertial confinement fusion, soft X-ray spectrum unfolding can provide important information to optimize the design of the laser and target. As the laser beams increase, there are limited locations for installing detection channels to obtain measurements, and the soft X-ray spectrum can be difficult to recover. In this paper, a novel recovery method of soft X-ray spectrum unfolding based on compressive sensing is proposed, in which (1) the spectrum recovery is formulated as a problem of accurate signal recovery from very few measurements (i.e., compressive sensing), and (2) the proper basis atoms are selected adaptively over a Legendre orthogonal basis dictionary with a large size and Lasso regression in the sense of ℓ1 norm, which enables the spectrum to be accurately recovered with little measured data from the limited detection channels. Finally, the presented approach is validated with experimental data. The results show that it can still achieve comparable accuracy from only 8 spectrometer detection channels as it has previously done from 14 detection channels. This means that the presented approach is capable of recovering spectrum from the data of limited detection channels, and it can be used to save more space for other detectors. [ABSTRACT FROM AUTHOR]