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Development of improved higher-order correction for the NIF opacity spectrometer
B A Hobbs1, D C Mayes1, R F Heeter2
1The University of Texas at Austin, Department of Astronomy, Austin, Texas 78712, USA.
The Review of Scientific Instruments
|August 19, 2024
Summary
New methods improve X-ray opacity measurements for oxygen and iron plasmas at the National Ignition Facility (NIF). This enhances understanding of solar models and white dwarf stars by correcting spectral data.
Area of Science:
- Plasma physics
- Astrophysics
- Spectroscopy
Background:
- X-ray opacity measurements are crucial for understanding stellar interiors, including the Sun and white dwarf stars.
- Previous opacity measurements at the Sandia Z Facility are being reproduced at the National Ignition Facility (NIF).
- Accurate soft X-ray spectroscopy requires corrections for higher-order diffraction effects.
Purpose of the Study:
- To develop and validate a new method for correcting higher-order spectral components in NIF opacity spectrometer data.
- To improve the accuracy of X-ray opacity measurements for oxygen and iron plasmas.
- To support revised understanding of the solar problem and hot degenerate white dwarf structure.
Main Methods:
- Modeling absorption and backlighting continuum spectra.
- Subtracting second- and third-order spectral components from measured data.
- Extending prior work on correcting higher-order diffraction effects in Bragg crystal spectrometers.
Main Results:
- A novel method was developed to remove higher-order spectral components from NIF opacity data.
- The method successfully corrects for second- and third-order diffraction effects.
- The correction process avoids introducing artifacts from first-order model line features.
Conclusions:
- The new method enhances the accuracy of X-ray opacity measurements from NIF.
- Improved opacity data will refine models of solar composition and white dwarf stars.
- This work advances the capability of soft X-ray spectroscopy for plasma diagnostics.
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