Electron beam ion-charge breeding source and related vacuum issues

There is a proposal to develop an electron beam ion-charge breeding source (EBIBS) to produce a highly charged and highly pure ion beam of common elements as well as rare isotopes. The report explains certain design choices and constraints involved in developing the EBIBS. Trajectory simulation of electron beams in 10 Amp range has been done to determine the configuration of electrodes and magnet coils appropriate to obtain high current density electron beam at the drift tube region starting from the electron gun to the water cooled electron collector. The EBIBS consists of an electron gun chamber, the main solenoid chamber and an electron collector chamber for attaining highly charged and pure ion beam of stable or radioactive species. The background pressure in the trap region should be low enough that one does not produce a significant number of ions from the background gas. An impurity value of the order of ∼5% can be tolerated, so an acceptable range of vacuum in EBIBS, 10^-1010^-12 mbar, is assumed, which determines requirements to the vacuum technology. All the internal components employ materials suitable for an ultra high vacuum. The system will stay continuously under vacuum except when repairs are needed. Cryo-pumps, turbo-molecular pumps, NEG pumps, titanium sublimation pumps and ion pumps together make up the pumping system. Turbo-molecular pumps bring it down initially to the 10^-6 mbar range and subsequently ion pumps or cryo-pumps take over. (author)