Journey from ECR ion source to Linac: a 60 M beam transport system for HCI

The high temperature superconducting ECR ion source produces a beam of multiply charged ions with high currents which have to be successfully transported to superconducting LINAC through a very long beam transport system around 60m. The beam is energized by 200kV high voltage DECK, radio frequency quadrupole (RFQ) and a drift tube linac before entering into SCLINAC. The beam transport system is divided into low, medium and high energy transport sections namely LEBT, MEBT and HEBT respectively. The ion beam is bunched by a multiharmonic buncher (MHB) and subsequently by spiral bunchers at different locations. The transverse and longitudinal optics has been studied using the codes like TRANSPORT, GICOSY and TRACE3D. The beam is transported with minimum emittance growth and phase spread so as to match in all the phase spaces to the next device properly in each transport section. The LEBT section uses the set of electrostatic and magnetic quadrupoles to match the beam into RFQ transversely. The MEBT section matches the beam from exit of RFQ to input of DTL with phase compensations using spiral buncher. The HEBT is longest section which contains the four achromatic 90 deg. bends to transport the beam of 0.5 to 1% energy spread. The whole beam optics layout is drawn so as to take into account of proper radiation safety as well as the adequate space for beam diagnostics. (author)