Recursive algorithm for fast evaluation of the Abel inversion integral in broadband reflectometry

The application of Kalman filtering is proposed for the numerical evaluation of plasma density profiles using noisy group delay data obtained from O-mode frequency-modulated broadband reflectometry. This method allows faster computation of the Abel inversion integral than the usual numerical methods (e.g., the trapezoidal rule) while maintaining a good accuracy in the presence of noise. In addition, density profiles with different degrees of smoothing can be produced by adjusting a single parameter. The algorithm seems promising in applications to plasma control in real time.