MEASUREMENTS ON THE EFFICIENCY OF ACOUSTIC DELAY-LINES IN VIEW OF BEAM LINES FOR SYNCHROTRON RADIATION

Tests have been run to study the propagation of a pressure wave as originated by the rupture of a beam exit foil window in the beam line of a synchrotron radiation storage ring. The measured velocities were approximately 1000 m/s for air and 2000 m/s for helium. The influence of various acoustic delay lines on the propagation of such waves was studied by measuring the local dependence of the velocity in the pressure range of 10** minus **6 to 10** minus **3 mbar. Results show that the use of acoustic delay lines results in a drastic reduction of propagation velocity remaining at the same low level even in the part of the beam line behind the delay line. The efficiency of a delay line as defined by the ratio of inlet versus outlet velocity is determined mainly by its geometry and changes little with type of gas.