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Electron density profile measurements from hydrogen line intensity ratio method in Versatile Experiment Spherical
YooSung Kim1, Yue-Jiang Shi1, Jeong-Hun Yang1
1Department of Nuclear Engineering, Seoul National University, Seoul 151-744, South Korea.
The Review of Scientific Instruments
|December 3, 2016
Summary
Researchers measured electron density in spherical torus plasmas using a hydrogen line intensity ratio method. This technique, employing a fast camera, provides accurate plasma diagnostics and agrees with probe measurements.
Area of Science:
- Plasma physics
- Fusion energy research
- Atomic and molecular physics
Background:
- Accurate measurement of electron density is crucial for understanding and controlling plasma behavior in fusion devices.
- Spherical tokamaks present unique challenges for plasma diagnostics due to their compact geometry.
- Optical methods offer non-intrusive ways to probe plasma properties.
Purpose of the Study:
- To develop and validate a novel optical method for measuring electron density profiles in versatile experiment spherical torus plasmas.
- To demonstrate the capability of a fast-framing camera system for simultaneous detection of Balmer line emissions.
- To compare the results obtained from the optical method with traditional probe measurements.
Main Methods:
- Utilized a hydrogen line intensity ratio method to determine electron density.
- Employed a fast-frame visible camera with bandpass filters to capture simultaneous Hα and Hβ emissions.
- Implemented an optical system with a frame rate of 1000 fps and spatial resolution of 0.5 cm.
- Obtained one-dimensional local emissivity profiles from toroidal line-of-sight measurements with viewing dumps.
Main Results:
- Successfully measured electron density profiles in spherical torus plasmas.
- Demonstrated simultaneous imaging of Hα and Hβ radiation using a single camera system.
- Initial electron density profile results showed reasonable agreement with measurements from a triple Langmuir probe.
Conclusions:
- The hydrogen line intensity ratio method, coupled with a fast-framing camera, is a viable technique for electron density diagnostics in spherical torus plasmas.
- The developed optical system provides high temporal and spatial resolution for plasma measurements.
- This non-intrusive method offers a reliable alternative or complement to probe-based diagnostics in fusion research.
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