Abstract
It has been shown that microwave intensities of about 0.4 mW cm-2 in the control room of the Sagittaire accelerator can interfere with the functioning of the accelerator and result in a higher beam energy. Increases in beam energy of up to 14% were measured. This was the result of direct interference with the beam bending system. However, the increase in beam bending current indirectly influences the acceleration of the electrons (and thus the electron energy) via feedback circuits for gun-emission and RF-power. No significant influence of microwaves upon the dosimetry system of this accelerator was found. This is in contrast with the earlier findings of Kopeckey and Purdy (1980). The TLD experiment showed that placing an absorbing medium in front of the antenna reduces the interference but does not completely remove it. In the clinical set-up the patient himself will be the absorbing medium for the microwaves. However, it is doubtful whether this will result in a further decrease or disappearance of the interference effects.