LU-10 single-section electron Linac was commissioned in 1987 [1]. Up to mid 1993 it had operated on KIU-53 klystron, producing electron beam with output energy within the maximum power spectrum Ej max ≅10 MeV and average current Iav≅500 μa at a rep rate N=150 1/ sec. A necessity arose in 1993 to increase beam energy and output power. However, by this time KIU-53 klystrons were no longer produced by industry with only KIU-12 klystrons being available for this purpose. Since KIU-12 has the pulsed power operation value Ppul≅(20÷18)MW at N≅(50÷100) 1/sec, respectively, then, it was necessary that N be raised up to 300 s-1 with increasing Ppul up to (24÷26)MW, the decision was taken to upgrade the rf-power input source for the LU-10 accelerating section and employ in the new LU-10M a scheme of adding up the rf-power output from both KIU-12 klystrons. The earlier studies [2] gave a reason to believe that such a set-up should provide for a reliable operation of the accelerator and required beam parameters at N=300 1/sec and the power input operation Ppul≅(12÷13)MW from each of the two KIU-

A beam with two energy peaks is used in a two-section linear electron accelerator. A typical energy distribution of the two-component beam is shown.

An experimental investigation was made of the amplitude of acoustic pulses excited in a thin plate by a fast-electron beam. The measurements were carried out in the electron energy range 40--1300 MeV. The dependence of the acoustic pulse amplitude on the electron energy agreed with the corresponding dependence of the ionization losses in the target material. The absolute amplitude of the acoustic signal was in order-of-magnitude agreement with the estimates obtained on the basis of the thermo-elastic mechanism on the assumption of complete transformation of the ionization losses of the electron energy into heat. (AIP)