Injector and Main Linac Fumio Furuta, Peter Quigley Cornell - PowerPoint PPT Presentation

Injector and Main Linac Fumio Furuta, Peter Quigley Cornell University ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 1/30

Outline  Introduction  Injector status  Main Linac status  Next steps ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 2/30

Introduction Injector Cyomodule (ICM): Field stability requirements: • High beam loading • σ A /A ∼ 1 ･ 10 -3 • Small Q L ∼ 5 ･ 10 4 to 4 ･ 10 5 • σ Φ ∼ 1 deg • Large bandwidth Δf ∼ 2 to 13 kHz 6 MeV +/- 36 MeV Main Linac Cyomodule (MLC): • No (almost) beam loading • Field stability requirements: • High Q L ∼ 6 ･ 10 7 • σ A /A ∼ 1 ･ 10 -4 • Small bandwidth Δf ∼ 10 Hz • σ Φ ∼ 0.15 deg 42, 78, 114, 150 MeV ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 3/30

Injector Cryomodule http://www.classe.cornell.edu/Research/SRF/SrfNews2010.html ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 4/30

ICM and parameters ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 5/30

ICM past performances in L0E Intrinsic quality factor Q vs. accelerating field Eacc of the injector SRF cavities at 1.8K after rework of the cryomodule. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 6/30

ICM past performances in L0E Coupler Pulse Processing Pulse processing (1.5 msec, 50 Hz) of new couplers installed in the injector cryomodule Processing history Time required to reach 50 kW ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 7/30

ICM status  Injector Cryomodule (ICM): • Installed in L0E. • Completed 4K cooldown on 06/09/2016. • Performed 2K pump-down for system check on 06/15/2016. Returned to 4K operation. • Currently operating at 4K. • LLRF connections in progress. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 8/30

ICM in L0E ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 9/30

ICM status  Injector Cryomodule (ICM): • Helium vessel to insulation vacuum leak: • This leak has existed since 2009 L0 installation. Installed active pumping turbo and successfully operated ICM without issue. • For the L0E ICM installation, vacuum vessel is actively pumped with two 150 L/s turbo pumps and activated charcoal bags mounted in vacuum vessel. • At room temperature: • Base Pressure: 1e-5 torr. • Leak rate: ~6e-5 torr-liter/sec. • At 4K operation: • Base pressure: 4e-7 torr. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 10/30

ICM status  Klystrons: • Installed on L0E Mezzanine • All power, water, instrumentation, LLRF connected. • RF waveguide 98% installed. Final component installation in progress.  Initial RF power testing is tentatively scheduled to start the week of 08/01. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 11/30

120kW Klystrons in L0E ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 12/30

Injector, Next steps After turn RF on ,,, • LLRF system check. • Coupler conditioning. • Measure Q vs E. • HOM calibration. • Check HP helium gas cooling (needs operating couplers at high forward power). • coordinate with gun staff and others to get 1 mA through the injector to the dump. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 13/30

Main Linac Cryomodule Image; moving MLC to Wilson lab, Mar2015. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 14/30

7-cell cavities and MLC parameters Un-stiffened Cavity Stiffened Cavity ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 15/30

Magnetic shielding Three layers of magnetic shielding: - Vacuum Vessel (carbon steel) - 80/40 K magnetic shield enclosing the cold mass - 2 K magnetic shield enclosing individual cavities ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 16/30

MLC Cooling schematic the chimney on 2K2P line to HGRP Cavity string and Rad monitor notes Cavity#1 Cavity#2 Cavity#3 Cavity#4 Cavity#5 Cavity#6 ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 17/30

MLC test • Cavity RF test • Tuner test • HOM scan • Microphonics meas. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 18/30

MLC cavity RF test Quench Limit. Admin. Admin. Admin. FE Admin. 16 14 *FE processed out. Eacc max [MV/m] 12 10 8 6 4 Test results of Max fields at 1.8K 2 0 1 2 3 4 5 6 cavity# • 5 of 6 cavities had achieved MLC design gradient of 16.2MV/m at 1.8K in MLC. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 19/30

MLC cavity Q 0 at 16.2MV/m, 1.8K *Q 0 at 14MV/m, FE started. Target Qo 2.0e10 at 1.8K Qo at 16.2MV/m 1.00E+10 *Q 0 after FE *Q 0 at 16.2MV/m *Q 0 after many quench. processed out. with severe FE. 1.8K 1.00E+09 0 2 4 6 cavity# • 4 of 6 cavities had achieved design Q 0 of 2.0E+10 at 1.8K. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 20/30

Thermal cycles on MLC Top dT vertical Rate; ~36K/min. dT vertical ; ~36K near Tc bottom Rate; ~0.13K/h • Plot shows the temp. profiles on dT vertical; ~0.6K top and bottom of Helium tank. dT vertical near Tc • To pass through the Tc • Fast cool down w/ large dT ; ~ 10min. for 6 cavities. • Slow cool down w/ small dT ; ~ 20hrs for 6 cavities. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 21/30

Impact of thermal cycling MLC cavity #1 MLC cavity #3 MLC cavity #2 Q0 1E+10 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 Eacc [MV/m] Eacc [MV/m] Eacc [MV/m] MLC cavity #5 MLC cavity #4 MLC cavity #6 FE processed out Quench limit, FE free 1.00E+10 Q0 Q0 Qo after RF processing 1.00E+09 1E+10 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 Eacc [MV/m] Eacc [MV/m] Eacc [MV/m] Thermal cycle with small temp. gradient over cavity improved Qo. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 22/30

MLC tuner test Tune has been done on all six cavities in 1.8K, successfully. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 23/30

HOM scan analysis Dipole HOMs on MLC were strongly damped below Q~10 4 . Consistent with HTC and simulation results. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 24/30

Microphonics meas. (1) • Preliminary results of mechanical vibration peaks on MLC. • stiffened and un-stiffened cavities had similar peak. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 25/30

Microphonics meas. (2) Initial measurements showed, • Stiffened cavities had ~30Hz detuning, Un-stiffened cavities had ~150Hz detuning (ERL design ~20Hz, CBETA 50~100Hz). • MLC had no optimization against detuning when these data were taken. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 26/30

Microphonics meas. (3) • the vibration peak of ~60Hz seemed to make high gain on detuning on un-stiffened cavities. • Identification of vibration source, vibration-elimination or isolation are needed. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 27/30

Identify and isolate the vibration sources ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 28/30

Main Linac, Next steps • Cooling down to 1.8 K again, re-instate running conditions. • Run LLRF and analyse free run data. • Analyse pressure sensor data (1.8 K system) • Take more accelerometer data. • Add pneumatic dampers to pump-skids and other vibrations generators. • Measure HOM spectra of the remaining cavities. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 29/30

Summary • Injector and Main Linac are commissioned, tested, and ready for CBETA. • Some optimization remains for the MLC. • Injector cryomodule will be turned RF on next week, the week of Aug. 1 st . LLRF system check, coupler conditioning, Qo meas., and HOM meas. are planed. • Main Linac Cryomodule is maintained at 4K currently, waiting cool down to 1.8K again. more optimizations for LLRF and microphonics are planed. ff97@cornell.edu, pgq1@cornell.edu CBETA Review, 27 July 2016 30/30