The automatic control of the Eindhoven A.V.F. Cyclotron, I: Measuring equipment

For the automatic control of the Eindhoven A.V.F. cyclotron the HF phase angle, the intensity, the extraction efficiency and the horizontal position of the external beam before the magnetic channel are measured continuously and without interception of the beam. For this purpose the signals from capacitive pick?up probes are measured using sampling and correlating techniques. With this experimental set?up intensities of 20 nA are measured and phase variations of 0.1 degree and position variations of 0.1 mm for a beam intensity of 10 ?A have been detected. The horizontal and vertical dimensions of the beam in the beam transport system are measured by means of a number of vibrating beam scanners with an accuracy of 0.2 mm down to intensities of 10 nA. The relation between cyclotron parameters and beam properties is assumed to be linear for small variations and is represented by a matrix. Some of the matrix elements can vary slowly in time. They are measured continuously by pulsing the cyclotron parameters involved and correlating the beam response with the small perturbing pulses. All measured data will be supplied to a PDP-9 computor via a CAMAC modular data handling system