Thermal analysis of 75 MHz heavy ion radio frequency quadrupole

Development of heavy ion radio frequency quadrupole (RFQ) resonant cavity is in progress at BARC. The RFQs are considered to be the most efficient accelerating structure for ion beam at lower energies. The resonating frequency of the structure depends on the internal geometry of the cavity. Thus to operate an RFQ at operational frequency a tuner is an essential element, which takes care of variation in geometry due to mechanical constraints. When structure is conditioned to RF power, heat dissipation causes thermal deformation and hence dimensional changes. This deformation will change vacuum space, and therefore resonant frequency. The tuners normally, do not compensate the effect of frequency shift due to thermal deformations which have significant control implications. It is very important to know the sensitivity of the RFQ for frequency shift due to thermal deflection. In this paper thermal deflection of RFQ vane has been investigated for coolant flow direction, various flow rate and coolant inlet temperature. Paper also presents modeling and results of the thermo-mechanical analysis. (author)