Beam profile measurements at MAX

An electron beam profile monitor system is described. It utilizes the visible bending magnet synchrotron radiation (SR) to form an image of the beam. A model for calculating diffraction and depth of field effects is introduced. Assuming a Gaussian distributed electron beam, the relation between beam image size and actual beam size is then calculated with this model, for a number of practical measuring situations. In a series of measurements at the MAX I electron storage ring at a current of 1 mA, the beam image size has been measured for these calculated situations. The measured values are presented, and their behaviour is in good agreement with the model. With this model the horizontal and vertical rms beam sizes were determined to σx = (203 ± 3) μm and σy = (19 ± 3) μm respectively. The corresponding vertical emittance is approximately 0.05 nm rad.