JLEIC SRF update SRF team 06-15-2017
Outline Prototype Storage Ring/ERL Cavities Harmonic fast kicker Magnetic momentum measurement cavity
Cavity Fabrication Status Production of 952.6 MHz cavities proceeding well 4 cavities in fabrication: 1 Nb 1-cell cavity 2 Cu 1-cell cavities 1 Nb 5-cell cavity Deep-drawing dies ready (heavy/bulky – hard labor work on press to form half cells) Need to modify 650 MHz RF measurement fixture for 952.6 MHz endgroups/dumbbells in progress
Cavity Fabrication Status Qty. Material Nb blanks for half cells for beam tubes Half cells deep-drawn Beam Tubes Flanges Endgroups 1-cell 1 Nb 2/2 – wire EDM completed wire EDM 2/2 - completed Completed/ machined (Nb flanges) 2/2 Welding completed Waiting for RF trim fixture 2 Cu 4/4 – wire EDM 4/4 - completed Rolled/ not machined yet SS CF flanges - to be ordered Not yet Started - 5-cell 10/10 – wire EDM 2/10 (new fixture in place to ease release of cells) In stock – not yet used started Single-cell Nb cavity endgroups ready, getting close to complete cavity
Harmonic fast kicker Baseline kicking scheme moving forward: Frequencies for kicker modes settled, six odd harmonics of 86.6MHz Needs to finalize other parameters such as kicking angle and aperture Vacuum model concept in progress Simplified one cavity 6 modes design Size similar to Yulu’s ½ model cavity, with 1 additional tuner (5+1) Asymmetric design: cavity needs to be optimized for minimal longitudinal R/Q Compatible for UITF/LERF tests Gun needs to operate at 136MHz reprate
Harmonic Kicker Frequencies and UITF/LERF Test 1497 𝑀𝐻𝑧× 7 22 =476.32𝑀𝐻𝑧 CEBAF/UITF/LERF RF PEP-II or JLEIC e-ring RF 2×476.32𝑀𝐻𝑧=952.64𝑀𝐻𝑧 JLEIC i-ring/ERL RF frequency 476.32𝑀𝐻𝑧 11 =43.3𝑀𝐻𝑧 Baseline JLEIC ERL gun laser reprate CCR turns 952.64𝑀𝐻𝑧 11 =86.6𝑀𝐻𝑧 harmonic kicker base RF 1497 𝑀𝐻𝑍 11 =136.1𝑀𝐻𝑧 photo cathode laser reprate in UITF/LERF test 136.1 𝑀𝐻𝑍 11 = 86.6 𝑀𝐻𝑍 7 =12.37 𝑀𝐻𝑧 kicked beam reprate in UITF/LERF test Odd harmonic frequencies of RF kicker: 86.6 MHz x1, x3, x5, x7, x9, x11 (or x0) =86.6MHz, 259.8MHz, 433.0 MHz, 606.2 MHz, 779.4 MHz, 952.6 MHz/DC CCR harmonic number can NOT be multiple of 11