5 K 60 70 K 250 * This value takes into account the actual voltage distribution on the HWR cavities. Therefore, it is smaller than the value presented in Table 2.7. Single Spoke Resonator I (SSR1) Cavities and Cryomodules Acceleration from 10 to 35 MeV utilizes superconducting cavities with = 0.222 operating at βopt 325 MHz, referred to as Single Spoke Resonator of type 1 or SSR1 (see Figure 3.37) [81]. Figure 3.37: Cut-away view of SSR1 cryomodule designed for PIP-II. RF Design and Optimization of SSR1 Cavities RF design and optimization of the SSR1 cavity was done using Microwave Studio (MWS) software. Figure 3.38 presents the main geometrical parameters used for optimization: is the LCAV cavity length, end-wall to end-wall along beam axis, is the iris to iris length, is the spoke LIRIS D base diameter, is the spoke width, is the inner electrode thickness, and and v are cylindrical W T h shell and end-wall dimensions. Beam dynamics considerations led to the choice of and a 30 β=0.21 mm aperture diameter. Also an iris-to-iris distance, = (2/3) was chosen. Table 3.4 lists the Liris βλ, general requirements to the electromagnetic parameters. Table 3.4: SSR1 electromagnetic parameters Parameter Value Frequency 325 MHz Shape Single Spoke Resonator 0.215, 0.22 g, opt 203 mm = opt Leff λ Iris aperture 30 mm Inside diameter 492 mm Bandwidth (f0/Q) 90 Hz 3.84 Epk/Eacc 5.81 mT/(MV/m) Bpk/Eacc 84 G Ω R/Q 242 Ω Figure 3.38: Cross section of the SSR1 with the main parameters used in the optimization process. Minimization of the peak surface electric field (Epeak) involves and as main W, T Liris parameters, since they define the geometry in the region of high electric field (see Figure 3.39). The ratio and the end cup profile dimensions were optimized to achieve a low peak magnetic D/Lcav field (see Figure 3.40). The corresponding electric and magnetic 3D fields are shown in Figure 3.41. The plots have been generated with Comsol software.
5 K 60 70 K 250 * This value takes into account the actual voltage distribution on the HWR cavities. Therefore, it is smaller than the value presented in Table 2.7. Single Spoke Resonator I (SSR1) Cavities and Cryomodules Acceleration from 10 to 35 MeV utilizes superconducting cavities with βopt = 0.222 operating at 325 MHz, referred to as Single Spoke Resonator of type 1 or SSR1 (see Figure 3.37) [81]. Figure 3.37: Cut-away view of SSR1 cryomodule designed for PIP-II. RF Design and Optimization of SSR1 Cavities RF design and optimization of the SSR1 cavity was done using Microwave Studio (MWS) software. Figure 3.38 presents the main geometrical parameters used for optimization: LCAV is the cavity length, end-wall to end-wall along beam axis, LIRIS is the iris to iris length, D is the spoke base diameter, W is the spoke width, T is the inner electrode thickness, and h and v are cylindrical shell and end-wall dimensions. Beam dynamics considerations led to the choice of β=0.21 and a 30 mm aperture diameter. Also an iris-to-iris distance, Liris = (2/3) βλ, was chosen. Table 3.4 lists the general requirements to the electromagnetic parameters. Table 3.4: SSR1 electromagnetic parameters Parameter Value Frequency 325 MHz Shape Single Spoke Resonator g, opt 0.215, 0.22 Leff = opt λ 203 mm Iris aperture 30 mm Inside diameter 492 mm Bandwidth (f0/Q) 90 Hz Epk/Eacc 3.84 Bpk/Eacc 5.81 mT/(MV/m) G 84 Ω R/Q 242 Ω Figure 3.38: Cross section of the SSR1 with the main parameters used in the optimization process. Minimization of the peak surface electric field (Epeak) involves W, T and Liris as main parameters, since they define the geometry in the region of high electric field (see Figure 3.39). The ratio D/Lcav and the end cup profile dimensions were optimized to achieve a low peak magnetic field (see Figure 3.40). The corresponding electric and magnetic 3D fields are shown in Figure 3.41. The plots have been generated with Comsol software.
PIP-II_CDR_v.0.1.work2.docx