  A room temperature heavy ion linac has been proposed as a new injector of
CSRm (the main Cooler Storage Ring) at HIRFL (Heavy Ion Research Facility in
Lanzhou), which is expected to improve the performance of HIRFL. The linac
injector can supply heavy ion with maximum mass to charge ratio of 7 and
injection kinetic energy of 7.272MeV/u for CSRm, and the pulsed beam intensity
is 3emA with the duty factor of 3%. Compared with the present cyclotron
injector SFC (Sector Focusing Cyclotron), the beam current from linac can be
improved by 10-100 times. As the pre-accelerator of the linac, the 108.48MHz
4-rod RFQ accelerates ion beam from 4keV/u to 300keV/u, which achieves the
transmission efficiency of 95.3% with 3.07m long vanes. The phase advance has
been taken into account to analysis the error tolerance, and parametric
resonance have been carefully avoided by adjusting the structure parameters.
KONUS IH-DTLs, which follow the RFQ, accelerate the ions up to the energy of
7.272MeV/u and inject into HIRFL-CSRm. The resonance frequency is 108.48MHz for
the first two cavities and 216.96MHz for the last 5 DTLs. The maximum
accelerating gradient can reach 4.95MV/m in DTL section with the length of
17.066m, and the total pulsed RF power is 2.8MW. A new strategy, for the
determination of resonance frequency, RFQ vane voltage and DTL effective
accelerating voltage, is described in detail. The beam dynamics design of the
linac will be present in this paper.
