Sample interview questions: How would you approach the problem of plasma stability control in a non-axisymmetric experimental setup with multiple instabilities?
Sample answer:
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Identify the Dominant Instabilities:
Start by identifying the dominant instabilities present in the experimental setup. Common instabilities in non-axisymmetric plasmas include tearing modes, interchange modes, and kink modes. Understanding their characteristics, growth rates, and driving mechanisms is essential for developing effective control strategies. -
Assess the Global Magnetic Field Configuration:
Analyze the global magnetic field configuration, including the toroidal and poloidal fields, to determine the stability boundaries and regions of high instability drive. This assessment helps identify potential locations for targeted control interventions. -
Develop a Physics-Based Model:
Construct a physics-based model that captures the essential dynamics of the plasma instabilities. This model can be used to simulate the plasma behavior and predict the effects of various control actuators on the instability growth. -
Design Feedback Control Algorithms:
Design feedback control algorithms based on the developed model and the identified dominant instabilities. Common control techniques include proportional-integral-derivative (PID) controllers, state-space controllers, and optimal control algorithms. The specific choice of control algorithm depends on the system dynamics and desired performance object… Read full answer