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Measuring magnetic field vector components with quantum beat spectroscopy
Tyler J Gilbert1, Jacob W McLaughlin2, Krishan Kumar2
1Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195, USA.
The Review of Scientific Instruments
|May 6, 2026
Summary
Quantum beat spectroscopy now measures magnetic field orientation in plasmas. This advanced technique provides precise vector magnetic field measurements with high spatial and temporal resolution.
Area of Science:
- Plasma physics
- Laser spectroscopy
- Magnetohydrodynamics
Background:
- Magnetic fields are crucial in various plasma environments, including fusion and space plasmas.
- Quantum beat spectroscopy offers precise magnetic field strength measurements in gases like argon and helium.
Purpose of the Study:
- To extend quantum beat spectroscopy for determining magnetic field orientation and direction.
- To analytically calculate magnetic field vector components using phase shifts of quantum beat amplitudes.
Main Methods:
- Utilizing quantum beat spectroscopy with measurements at three distinct polarization angles.
- Analyzing phase shifts of quantum beat amplitudes to determine magnetic field vector components.
- Validating the technique by correlating known magnetic field angles with measured phase shifts.
Main Results:
- Successfully determined magnetic field orientation and, in a specific case, absolute direction.
- Achieved a standard deviation of 5.7° in correlating known angles with measured phase shifts.
- Estimated uncertainty in calculated magnetic field components is below 10%.
Conclusions:
- Quantum beat spectroscopy is a viable method for vector magnetic field measurements in plasmas.
- The expanded technique offers high precision and resolution for plasma diagnostics.
- This advancement has implications for understanding magnetic phenomena in fusion and space plasmas.
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