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Title: High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100–300 Å spectral band

Abstract

We have constructed a high-resolution grazing-incidence spectrometer designed for measuring the ion temperature of low-Z elements, such as Li{sup +} or Li{sup 2+}, which radiate near 199 Å and 135 Å, respectively. Based on measurements at the Livermore Electron Beam Ion Trap we have shown that the instrumental resolution is better than 48 mÅ at the 200 Å setting and better than 40 mÅ for the 135-Å range. Such a high spectral resolution corresponds to an instrumental limit for line-width based temperature measurements of about 45 eV for the 199 Å Li{sup +} and 65 eV for the 135 Å Li{sup 2+} lines. Recently obtained survey spectra from the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory show the presence of these lithium emission lines and the expected core ion temperature of approximately 70 eV is sufficiently high to demonstrate the feasibility of utilizing our high-resolution spectrometer as an ion-temperature diagnostic.

Authors:
; ;  [1]; ; ;  [2]
  1. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
  2. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
Publication Date:
OSTI Identifier:
22303695
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ELECTRON BEAMS; EV RANGE 10-100; ION EMISSION; ION TEMPERATURE; LINE WIDTHS; LITHIUM IONS; RESOLUTION; SPECTROMETERS; TEMPERATURE MEASUREMENT; TOKAMAK DEVICES

Citation Formats

Widmann, K., E-mail: widmann1@llnl.gov, Beiersdorfer, P., Magee, E. W., Boyle, D. P., Kaita, R., and Majeski, R. High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100–300 Å spectral band. United States: N. p., 2014. Web. doi:10.1063/1.4894388.
Widmann, K., E-mail: widmann1@llnl.gov, Beiersdorfer, P., Magee, E. W., Boyle, D. P., Kaita, R., & Majeski, R. High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100–300 Å spectral band. United States. doi:10.1063/1.4894388.
Widmann, K., E-mail: widmann1@llnl.gov, Beiersdorfer, P., Magee, E. W., Boyle, D. P., Kaita, R., and Majeski, R. Sat . "High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100–300 Å spectral band". United States. doi:10.1063/1.4894388.
@article{osti_22303695,
title = {High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100–300 Å spectral band},
author = {Widmann, K., E-mail: widmann1@llnl.gov and Beiersdorfer, P. and Magee, E. W. and Boyle, D. P. and Kaita, R. and Majeski, R.},
abstractNote = {We have constructed a high-resolution grazing-incidence spectrometer designed for measuring the ion temperature of low-Z elements, such as Li{sup +} or Li{sup 2+}, which radiate near 199 Å and 135 Å, respectively. Based on measurements at the Livermore Electron Beam Ion Trap we have shown that the instrumental resolution is better than 48 mÅ at the 200 Å setting and better than 40 mÅ for the 135-Å range. Such a high spectral resolution corresponds to an instrumental limit for line-width based temperature measurements of about 45 eV for the 199 Å Li{sup +} and 65 eV for the 135 Å Li{sup 2+} lines. Recently obtained survey spectra from the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory show the presence of these lithium emission lines and the expected core ion temperature of approximately 70 eV is sufficiently high to demonstrate the feasibility of utilizing our high-resolution spectrometer as an ion-temperature diagnostic.},
doi = {10.1063/1.4894388},
journal = {Review of Scientific Instruments},
number = 11,
volume = 85,
place = {United States},
year = {Sat Nov 15 00:00:00 EST 2014},
month = {Sat Nov 15 00:00:00 EST 2014}
}
  • In this paper, we have constructed a high-resolution grazing-incidence spectrometer designed for measuring the ion temperature of low-Z elements, such as Li + or Li 2 +, which radiate near 199 Å and 135 Å, respectively. Based on measurements at the Livermore Electron Beam Ion Trap we have shown that the instrumental resolution is better than 48 mÅ at the 200 Å setting and better than 40 mÅ for the 135-Å range. Such a high spectral resolution corresponds to an instrumental limit for line-width based temperature measurements of about 45 eV for the 199 Å Li+ and 65 eV formore » the 135 Å Li 2 + lines. Finally, recently obtained survey spectra from the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory show the presence of these lithium emission lines and the expected core ion temperature of approximately 70 eV is sufficiently high to demonstrate the feasibility of utilizing our high-resolution spectrometer as an ion-temperature diagnostic.« less
  • A high-resolution grazing-incidence grating spectrometer has been implemented on the Livermore electron beam ion traps for performing very high-resolution measurements in the soft x-ray and extreme ultraviolet region spanning from below 10 Å to above 300 Å. The instrument operates without an entrance slit and focuses the light emitted by highly charged ions located in the roughly 50 μm wide electron beam onto a cryogenically cooled back-illuminated charge-coupled device detector. The measured line widths are below 0.025 Å above 100 Å, and the resolving power appears to be limited by the source size and Doppler broadening of the trapped ions.more » Comparisons with spectra obtained with existing grating spectrometers show an order of magnitude improvement in spectral resolution.« less
  • Comparative studies have been made on the holographic plane grating and the ruled varied-line-spacing (VLS) plane grating designed for two kinds of objective Monk{endash}Gillieson type high-resolution grazing incidence monochromator, I and II. The ray-traced performance of monochromator types I and II on a synchrotron radiation beam line was evaluated in terms of resolving power and spectral purity by the introduction of new concepts of effective Gaussian line and purity profiles. The resolving power defined on the basis of the effective Gaussian profile is consistent with the spectral purity of the beam emerging from the exit slit and is more realisticmore » as compared with those defined in the conventional manner, especially when spectral images have asymmetric profiles. It is concluded that holographic plane gratings recorded with a spherical and an aspheric wave front are capable of providing high resolution with high spectral purity and are fully interchangeable with the corresponding ruled VLS plane gratings. This interchangeability provides more flexibility for users in choosing a proper grating for a high-resolution grazing incidence monochromator of the Monk{endash}Gillieson type. {copyright} 1997 Optical Society of America« less
  • We have performed an initial design study on a single-element aberration-corrected holographic toroidal spectrometer for use in diagnosing extreme ultraviolet laser amplifiers that we plan to study as part of our tabletop extreme ultraviolet laser project at MIT. The spectrometer is designed to be 7 m long from source to image with an incidence angle of 80{degree} and a 450-line/mm holographic grating. The instrument is designed to be nearly stigmatic between 100 and 300 A to sufficient precision to allow two-dimensional imaging with a 10-{mu}m resolution. As a spectrometer the ideal resolution (with a zero slit width and a 25-{mu}mmore » spatial resolution at the image) is designed to be {lambda}/{Delta}{lambda} {approx} 5000.« less
  • A grazing incidence monochromator consisting of a spherical mirror, a varied spacing plane grating, movable plane mirror, and a fixed exit slit has been designed by means of a hybrid design method which takes advantage of both the ray-tracing and analytic methods. In the design, higher-order suppression and on-blaze feature were also taken into consideration. A spectral resolving power of [similar to]30 000--70 000 is expected for the monochromator over a wavelength range of 0.5--10 nm when used on an undulator beamline at the Advanced Light Source.