Extraction efficiency optimization for the Eindhoven AVF cyclotron

This paper describes a substantial improvement of a control system which optimizes the extraction efficiency of the ion beam in the Eindhoven AVF cyclotron. The equipment used induces small perturbations in the currents of those coils with large influence on the extration process. The responses in the beam current after extraction are correlated with the perturbing pulses. The system consists of CAMAC modules with some external electronics. The timing, of the measuring and perturbing equipment, is controlled by a programmable CAMAC clock. An important part of the measuring equipment is a fast data logger, that performs the measurements of the extracted beam current. The correlation is performed by a PDP11 computer. An on-line least-squares parameter estimation method (learning procedure) is applied, which is used to determine the control matrix for extraction optimization. The extraction optimization system corrects slowly varying changes in certain cyclotron parameters such as drift of the magnetic field, to preserve maximum external beam current