COMPARISON OF THE BEAM DYNAMICS DESIGNS FOR THE FAIR HIGH CURRENT PROTON LINAC-RFQ

The antiproton physics program for future Facility for Antiproton and Ion Research (FAIR) at Darmstadt is based on a rate of 7x10 10 cooled antiprotons per hour. To provide sufficient primary proton intensities a new proton linac is planned. The proposed linac comprises a 100 mA proton source, a Radio Frequency Quadrupole (RFQ), and Crossed-bar H-cavities (CH-DTL). Its operation frequency of 352 ** MHz allows for an efficient acceleration to up to 70 MeV using normal conducting CH-DTLs. The beam pulses with a length of 36 mks, a current of 70 mA, and total transverse emittances of 7 mkm will allow to fill the existing GSI synchrotron SIS 18 within one multi-turn-injection up to its space charge limit of 7x10 12 protons. Conceptual RFQ designs for two different RFQ types are proposed simultaneously: an RFQ of 4-rod type from the University Frankfurt (Institute for Applied Physics, IAP) and a 4-vane type (with coupling windows) RFQ from the Institute for Theoretical and Experimental Physics (ITEP) and from the Moscow Radio-Technical Institute (MRTI). Studies of the beam dynamics for both RFQ designs have been done with the versatile multi-particle code DYNAMION under space charge conditions. The topology of the RFQ tanks and electrodes is used "as to be fabricated" to provide for realistic calculations of the external electrical field. The results simulated for both designs will be discussed, as well as pros and cons. A comparison simulation results performed with DYNAMION and the results obtained from dedicated RFQ design codes PARMTEQM and LIDOS is presented.