A new pulse compression system for intense relativistic electron beams

Abstract A special 360° deflection magnet has been installed at the exit of the 150 MeV Geel Electron Linear Accelerator (GELINA). It consists of five sectors with zero gradient fields and is designed to accept a 50% electron energy spread in the beam of the accelerator. This beam enters the magnet with a pulse width (fwhm) of typically 10 ns and leaves it with a pulse width (fwhm) of 0.6 ns. The peak current rises by this charge conserving compression from originally 10 A to about 100 A at the exit of the magnet. The compression is made possible by the time correlated electron energy degression caused by beam loading in the accelerator. The magnetic field effectuates a phase space transformation, translating the energy dispersion into a time correlated spread of trajectory lengths. This results in a delayed arrival of the leading edge of the pulse at the exit of the magnet as compared with the corresponding arrival of the trailing edge, which means a pulse compression. The pulse shape transformation by the magnetic field and the conditions for ideal pulse compression are analysed. This is followed by a description of the magnet with its electron optics and by a communication about the results and the operational experience.