Electromagnetic Design of a $\beta_{g} = 0.9$ 650-MHz Superconducting-Radio-Frequency Cavity

Abstract

Abstract:We present the electromagnetic design study of a multi cell,  g = 0.9, 650 MHz elliptic superconducting radiofrequency cavity, which can be used for accelerating H -particles in the linear accelerator part of a Spallation Neutron source. The design has been optimized for maximum achievable acceleration gradient by varying the geometry parameters of the cavity, for which a simple and general procedure is evolved that we describe in the paper. For the optimized geometry, we have studied the higher order modes supported by the cavity, and the threshold current for the excitation of the regenerative beam break up instability due to dipole modes has been estimated. Lorentz force detuning studies have also been performed for the optimized design and the calculations are presented to find the optimum location of the stiffener ring to compensate for the Lorentz force detuning.

Multipacting studies in elliptic SRF cavities

“…After having benchmarked our procedure for the analysis of multipacting, we next performed the calculations for  g = 0.61 [20] and  g =0.9 [21], 650 MHz, niobium based superconducting elliptical cavities, which are designed for Hparticle acceleration in the medium and high beta section of the proposed Indian Spallation Neutron Source (ISNS) project [20]. Theses cavities will be used to accelerate the Hparticle from 160 MeV to 1 GeV.…”

“…Multipacting prone range of E acc values for this cavity is obtained as E acc ~ 9.7-14.5 MV/m. In our case,  g =0.61 and  g =0.9 cavities are designed to be operated at E acc ~15.4 MV/m [20] and E acc =18.5 MV/m, respectively [21]. Hence, both the cavities may get infected by multipacting during their operation.…”

Study of impurity distribution in mechanically polished, chemically treated and high vacuum degassed pure niobium samples using the TOFSIMS technique

“…The medium and high energy section of this linac would consist of 650 MHz SCRF cavities made of Nb. The optimized target gradient of these cavities would be ~19 MV/m at proposed quality factor of ~10 10 [2] and should have minimum field emission (FE) and multipacting. The optimize performance of the cavities depends on the established sequence of standard chemical and thermal treatments.…”