2 nd harmonic Booster cavity. Status and plan. April 2, 2015 Gennady Romanov

2/IV-2015Gennady Romanov2 Current basic design Changes and corrections: Tapering now is included in basic design for more uniform bias field. Also it allows simplifying of simulations (will be explained). Gaps between cavity walls and yoke are closed Cooling cylinder excluded until final thermal simulations confirm its necessity. Garnet B(H) curve from experiments (name is Al800_exp_4 in CST material library) will be used. Garnet tanδ m as a function of μ ’ (or ΔH(μ ’ ) or μ ” (μ ’ ) or α (μ ’ )) will be used. Garnet tanδ e = assumed (larger value does not agree with experiment)

2/IV-2015Gennady Romanov3 Replacement of solenoid with uniform H_ext. Gain – reduced number of mesh cells Bob’s proposal – not very effective |H|bias, solenoid |H|external uniform Solenoid |H| along central line of ferrite Uniform external

2/IV-2015Gennady Romanov4 Taking into account experimental losses In this approach μ “ and μ ‘ are average over garnet volume, i.e. the field non-uniformity is not taken into account properly. Will be fixed in future with a help of 2D COMSOL simulations. From combination of these three functions ΔH will be defined for each frequency (or μ ’ ). In Shapiro’s paper ΔH=13÷100 Oe in interval μ ’ =2.4÷4. From our experiment an estimation is ΔH=3÷65 Oe in interval μ ’ =1.5÷3.6 (ΔH at f=9.4 GHz is meant for convenience, but actually it doesn’t matter since damping coefficient α ~ ΔH /f). In previous simulations ΔH was 31 Oe. Frequency domainEigenmode

2/IV-2015Gennady Romanov5 H_static H_rf Loss density First points H_ext=32 kA/m, F=75.6 MHzH_ext=120 kA/m, F=105.9 MHz H_static Loss density E_rf

2/IV-2015Gennady Romanov6 Thermal model T_max = 123 C° 4 kW of uniform losses