JLEIC SRF update SRF team 06 15 2017

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 Cavity Qty. Material Nb blanks for half cells Nb blanks for beam tubes Half cells deep-drawn Beam Tubes Flanges Endgroups Cavity 1 -cell 1 Nb 2/2 – wire EDM completed 2/2 - completed Completed/ machined (Nb flanges) 2/2 Welding completed Waiting for RF trim fixture 1 -cell 2 Cu 4/4 – wire EDM completed 4/4 - completed Rolled/ not machined yet SS CF flanges - to be ordered Not yet Started - 5 -cell 1 Nb 10/10 – wire EDM completed 2/10 (new fixture in place to ease release of cells) Completed/ machined In stock – not yet used Not yet 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. 6 MHz – 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 136 MHz reprate

Harmonic Kicker Frequencies and UITF/LERF Test CEBAF/UITF/ LERF RF PEP-II or JLEIC e-ring RF JLEIC i-ring/ERL RF frequency Baseline JLEIC ERL gun laser reprate CCR turns harmonic kicker base RF photo cathode laser reprate in UITF/LERF test kicked beam reprate in UITF/LERF test • Odd harmonic frequencies of RF kicker: 86. 6 MHz x 1, x 3, x 5, x 7, x 9, x 11 (or x 0) =86. 6 MHz, 259. 8 MHz, 433. 0 MHz, 606. 2 MHz, 779. 4 MHz, 952. 6 MHz/DC • CCR harmonic number can NOT be multiple of 11