Research School of Physics and Engineering, Australian National University, Canberra, Australia
A conventional corona control terminal voltage stabiliser has been investigated on the ANU 14UD tandem accelerator. The fluctuations in the charge transport of electrostatic pelletron generator and their correlation with mechanical oscillations of the chains and terminal voltage ripple have been analysed. Emphasis is placed on the performance of the two-loop feedback system and on the tuning of this system to production of high energy-resolution beams. The transfer function for the corona regulation loop has been determined and examined. The system produces the beam position at the image slit of the 90 energy-analysing magnet with long-term stability equivalent to a few hundred volts rms fluctuation of the terminal voltage. The concept of novel fast control loop utilizing the high-frequency component from the image slits to control the voltage of the last gap of high-energy acceleration tube is discussed.
