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A 100 KW Class Applied-field Magnetoplasmadynamic Thruster
Published on: December 22, 2018
A digital control system for external magnetohydrodynamic modes in tokamak plasmas
J M Hanson1, A J Klein, M E Mauel
1Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA. jmh2130@columbia.edu
The Review of Scientific Instruments
|May 2, 2009
Summary
A new feedback system uses advanced digital filtering and Kalman filters to precisely control magnetohydrodynamic activity in plasmas. This system enhances stability by accurately distinguishing plasma modes from background noise.
Area of Science:
- Plasma Physics
- Control Systems Engineering
- Applied Electromagnetics
Background:
- Magnetohydrodynamic (MHD) activity can destabilize plasma confinement in fusion devices.
- External MHD modes require active feedback control for mitigation.
- Existing control systems face challenges in resolving low-mode number activity and hardware-induced signal distortions.
Purpose of the Study:
- To develop and describe a novel feedback system for controlling external, long-wavelength magnetohydrodynamic activity.
- To enhance plasma stability through precise and responsive feedback control.
- To address limitations in current control methodologies for MHD phenomena.
Main Methods:
- Implementation of a control system with a network of localized magnetic pickup and control coils.
- Utilization of four independent, low-latency field-programable gate array (FPGA) controllers.
- Incorporation of digital spatial filtering for resolving low mode number activity.
- Application of temporal filtering to compensate for frequency-dependent hardware effects.
- Integration of a Kalman filter for robust signal processing and noise reduction.
Main Results:
- The system successfully demonstrates the capability to resolve low mode number MHD activity.
- Temporal filtering effectively corrects for amplitude and phase transfer effects inherent in the control hardware.
- The Kalman filter proves effective in distinguishing unstable plasma modes from noise, improving control accuracy.
- The integrated system provides precise feedback control over external MHD phenomena.
Conclusions:
- The described feedback system offers a significant advancement in controlling external MHD activity.
- The combination of advanced filtering techniques and FPGA controllers enables high-fidelity plasma control.
- This approach holds promise for improving plasma confinement and stability in future fusion reactors and other magnetohydrodynamic applications.
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