Measurement of the backstreaming ions produced by bremsstrahlung converter target of 12MeV LIA

Linac with mm diameter beam spot strikes the bremsstrahlung converter target to generate Ｘ-ray and the backstreaming ions.As ions move through the electron beam,the beam will be pinched which results in a moving focus before the target.Two sets of Faraday cup are combined designed to collect backstreaming ions produced at bremsstrahlung converter target of 12MeV linac. Analyses and comparison of numerical simulation and experiment results show that no backstreaming ions, close to targets between 6０° and 70°, are observed．