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An Experimental Protocol for Femtosecond NIR/UV - XUV Pump-Probe Experiments with Free-Electron Lasers
Published on: October 23, 2018
High-resolution time-resolved extreme ultraviolet spectroscopy on NSTX
J K Lepson1, P Beiersdorfer, J Clementson
1Space Sciences Laboratory, University of California, Berkeley, California 94720, USA. lepson@ssl.berkeley.edu
The Review of Scientific Instruments
|November 7, 2012
Summary
Upgraded spectrometers X-ray and Extreme Ultraviolet Spectrometer (XEUS) and Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS) at the National Spherical Torus Experiment (NSTX) now offer 12.5 ms time resolution. This advancement allows for detailed observation of plasma dynamics, such as iron evolution.
Area of Science:
- Plasma physics and spectroscopy
- Fusion energy research
- Instrumental advancements in extreme ultraviolet (EUV) and X-ray diagnostics
Background:
- The National Spherical Torus Experiment (NSTX) requires advanced diagnostic tools for plasma characterization.
- Flat-field grazing-incidence grating spectrometers are crucial for analyzing plasma emissions.
- Previous limitations in time resolution hindered the study of rapid plasma phenomena.
Purpose of the Study:
- To report on significant upgrades to the XEUS and LoWEUS spectrometers.
- To enhance the time resolution capabilities of these instruments for improved plasma diagnostics.
- To demonstrate the new capabilities by observing transient plasma behavior.
Main Methods:
- Upgraded the X-ray and Extreme Ultraviolet Spectrometer (XEUS) with a variable space grating (2400 lines/mm, 9-64 Å band).
- Enhanced the Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS) with a 1200 lines/mm grating (90-270 Å band).
- Integrated new cameras into both spectrometers to achieve 12.5 ms time resolution.
Main Results:
- Achieved a time resolution of 12.5 ms with the upgraded XEUS and LoWEUS spectrometers.
- Successfully demonstrated the new time resolution by capturing the time evolution of iron within the NSTX plasma.
- The upgraded instruments provide unprecedented temporal detail for plasma emission analysis.
Conclusions:
- The upgraded XEUS and LoWEUS spectrometers represent a significant advancement in NSTX plasma diagnostics.
- The enhanced time resolution enables detailed studies of fast plasma processes and impurity transport.
- These improvements will facilitate a deeper understanding of plasma behavior in fusion devices.
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