July LEReC Review July 2014 Low Energy RHIC electron Cooling Dmitry Kayran Beam commissioning

July Outline R&D ERL Staging of commissioning at BLDG 912 Status and milestones Parameters Commissioning at RHIC IP2 Milestones Summary 2

July Objectives of the R&D ERL program R&D ERL research goals: Demonstrate 300 mA, 20 MeV ERL Demonstrate 3.5 nC per bunch from the gun Study performance HOMs and Beam Breakup Emittance growth Halo With new C-AD projects/upgrades coming on line such as: –Low Energy RHIC electron Cooling (LEReC) The significance of ERL R&D program become even greater. The ERL R&D program was motivated by electron cooling for high energy RHIC and testing technology for future eRHIC upgrade It grew as resources became available Develop necessary tools, such as High QE photo-cathodes High current CW gun Well damped accelerating cavity Emittance preservation injection Beam instrumentation Machine protection

July R&D ERL layout at BLDG  Will serve as a test-bed for future RHIC projects: ERL-based electron cooling; 10-to-20 GeV ERL for electron-ion collider eRHIC; Low Energy RHIC electron cooler (LEReC).  Designed to test the key components of the High Current ERL based solely on SRF technology 704 MHz SRF Photo-injector: preservation of beam quality for high-charge, low emittance; High current 5-cell SRF linac test with HOM absorbers; Stability criteria for CW beam current; Attainable ranges of electron beam parameters in SRF ERL. Most of the existing ERL hardware (Gun, 5-cell cavity, magnets, diagnostics, powers supplies, beam dump) commissioned at ERL and then will be reused for LEReC.

July ERL commissioning at bldg 912. Some subsystems will be tested independently. The commissioning of ERL facility is logically broken down to several staging:  SRF components Cold Emission Tests (completed Nov 2013)  Gun first beam test (DOE approved, first test started June 2014)  Gun to Dump commissioning, subject of upcoming Accelerator Readiness Review (ARR), July 28-30, Injection line (low current) Extraction and beam dump (low current) High current Beam to Dump  Full ERL commissioning (future stage subject of ARR scheduled for Oct 2014) Our goal is to establish of ERL operation gradually and safely: All tests will be inside the ERL accelerator enclosure with a fully operational Access Control System. 5

July First beam test for SRF gun performance studies 6 Goals: Launch the first beam from the gun. Beam instrumentation setup/calibration Basic beam parameters measurements Main Parameters: Maximum Gun energy 2 MeV Multi-Alkali photocathode Laser pulse 8.5 psec Operating: single or/and train pulses limited average power 70 watts Charge pC Laser 10 MHz/10 Watts Available beam instrumentation: Faraday cup, FC (sensitivity 10pC) Integrating Current Transformer, ICT (sensitivity 10-50pC) Beam loss monitors Beam profile monitor

July Low power testing is ongoing in bldg DCCT YAG crystal Faraday Cup Pepper pot ICT Beam direction GUN Transport beam from the gun to the 5cell cavity through Zigzag Setup beam instrumentation Study beam quality after zigzag injection system

July Layout and components Gun to Dump stage. (BLDG 912) 8  The electron beam, generated in the SRF gun, is transmitted to the water cooled beam dump.  The beam is focused and guided by a collection of DC magnets.  The SRF accelerating cavity is off.  The operation of the SRF gun is controlled by RF electronics, including high-power amplifiers.  The ERL is equipped with beam instrumentation that measures the beam parameters and radiation level to detect potential beam losses.  The ERL is equipped with a machine protection system (MPS) that shuts off the beam, RF power or other components to protect the ERL equipment during commissioning.

July SRF Gun operation job flow at BLDG 912 ERL Cryogenic system is capable of providing 2K cold operation time of the SRF gun up to 16 hours in low power load mode After that it requires 2 days for helium recovery We will run the gun two days per week 9 1. Monday : Cool down the gun to 2 K, and stay at 2 K for 16 hours; then, warm up to 4.5 K; 2.Tuesday, Wednesday, the gun stays at 4.5K 3.Thursday: cool down the gun to 2K, stay there for 16 hours for beam test. 4.Friday, Saturday, Sunday, the gun stays at 4.5K. 5.Beam time / Cryogenic time about 20% Cavity at 2 K for 16 hours Beam time Cavity at 4.5K Helium recovery No beam Cavity at 2 K for 16 hours Beam time Cavity at 4.5K Helium recovery No beam MondayTue-WedThursdayFri-Sat-Su

July Gun to dump parameters and limitations 10 Existing System Maximum Capacity Needed for LEReC Gun Energy221.8 Photocathode tip materialCopperTa Photocathode QE, %0.211 Laser pulse, psec8.5 psec30 psec Charge per bunch, pC100 pC300 pC100 pC Peak current, A1233 Laser max. rep rate, MHz Average Current, mA SRF photoinjector upgrade: New 704 MHz LEReC laser system New cathode stalk with Ta tip HTS solenoid cooling system upgrade Bunch shape at the cathode: 8.5 psec 30 psec

July Goals of Gun to Dump commissioning stages Injection line commissioning (low current) –transport beam through the ERL injection line (ZigZag) –calibrate beam loss monitors –establish routine and fault dose rates external to the shielding Extraction and beam dump commissioning (low current) –transport beam through 5cell cavity and the ERL extraction line to beam dump –calibrate beam loss monitors and DCCTs –establish close to 100% beam to dump transport line propagation –carry out beam measurements –establish routine and fault dose rates external to the shielding High Intensity Studies (final stage) –demonstrate stable gun operation at minimum 30 mA average current –conduct cathode life time studies –beam dump commissioning –establish routine dose rates external to the shielding 11

July High intensity studies: Fault studies should be conducted at power level less then 20 Watts. 1) Establish Gun to dump operation at 5 uA beam current (10W) 2) Commissioning Beam Loss Monitors System 3) Adjust beam optics and corrector to minimize beam losses 4) Establish 50 uA beam current (100W) a)Check beam losses If necessary correct orbit to reduce beam losses in injection then extraction line. Compare ICT and DCCTs signals. b)Check beam dump performance. If necessary adjust optics in extraction line to provide more equal beam distribution in beam dump. c)Conduct radiation studies around beam line d)Examine dose from dump and on roof if possible. e)Conduct fault studies 5) Hold point: examine radiation levels and implement any adjustments required to go to the next phase; examine with RSC Chair if the dose rates are understood. 6) If radiation levels have been detected outside the shield they can be used to estimate the escalation to higher dose rates 7) Establish 500 uA (1kW) gun to dump repeat steps 4-6 8) Establish 5 mA (10kW) gun to dump repeat steps 4-6 9) Establish 30 mA (60kW) gun to dump repeat steps 4-6

July R&D ERL Loop commissioning 13 Main Parameters: Maximum injection energy 2.5 MeV Top energy 18 MeV Multi-Alkali photocathode Existing laser pulse: FWHM 8.5 psec, r=2mm Operating: single or/and train pulses Charge 100 pC Goals: Synchronization of SRF Gun, SRF Linac and Laser Commissioning rest of beam instrumentation (pepper pot, dipole profile monitors, halo monitors etc.) Measure beam position using BPM or/and minimum beam losses technic using BLMs. Conduct beam dynamics studies at low and high energy Learning the machine performance during previous commissioning phases allows to proceed with smooth transition to loop commissioning Loop magnets and instrumentation will be reused for the LEReC energy upgrade

July Status of R&D ERL commissioning (at Bldg. 912) Cathode deposition system and cathode transport cart operational 10 MHz laser system operational synchronized with LLRF SRF gun CW operation at 1.2 MV, performance improves after each run Beam instrumentation for first beam test installed and tested Magnets installed power supplies tested Beam dump installed

July Some Instrumentation installed under commissioning at bldg 912 Beam Profile monitor virtual target inspection BPM Block empty ERL Beam Position Monitor Bench Tests Halo Scrapers PMT Detectors

July May - Sept 2014: SRF Gun commissioning w/beam (in 912 blockhouse). Demonstrate 100 pC per pulse (pulsed operation) Perform Beam parameters ( charge, emittance, energy) measurements Oct-Dec 2014: SRF Gun to 5 cell to dump commissioning w/beam Demonstrate 1 mA average current operation Carry out beam loss studies Jan - June 2015: Shutdown for gun modifications and LEReC test preparation (in 912 blockhouse). No beam tests April-June 2015: 700 MHz LEReC laser system commissioning (in bldg 912) June June 2016: High current commissioning CW mode (LEReC tests in 912) Demonstrate 10 mA average current Commissioning 5cell cavity with beam. No acceleration. Measure beam parameters after 5cell cavity June 2016: Start moving equipment from bldg 912 (ERL site to IP 2 final location (LEReC) Timeline of LEReC commissioning at Bldg. 912

July Prerequisites: Cryo-system commissioned and operational RF system commissioned and operational Repeat 912 bldg commissioning steps at final location: SRF Gun re-commissioning Gun through 5 cell cavity to dump beam commissioning New steps Commissioning beam transport, cooling section magnets Cooling section beam instrumentation commissioning Staging of LEReC commissioning at IP2

July SRF gun re-commissioning Goals: Reestablish SRF gun stable operation Re-commissioning SRF injector beam instrumentation Measure beam parameters (charge, energy, energy spread) Faraday cup Flag SRF Gun Cathode transport

July LEReC Gun to dump Goals: Initiate stable operation at final location with local transport Measure beam quality required for LEReC after 5cell cavity (energy spread, emittance, charge, average current) Tune up beam instrumentation CW operation 1 mA Flag Beam Dump, FC 5 cell SRF cavity SRF Gun

July LEReC through cooling section Goals: Transport beam to/through/from cooling sections Commissioning beam instrumentation Measure beam quality required for LEReC at cooling section Energy spread < 5e-4 Angular spread < 150 um Charge per pulse 100 pC Stable CW operation average current 1 mA Beam losses control Cooling sections SRF gun with photocathode Transport to/from cooling section Beam dump

July Jun 2014-Jun 2016: SRF gun commissioning at BLDG 912 Jun 2016: Start moving equipment from bldg 912 (ERL site to IP 2 final location (LEReC) Jul 2016 – Apr 2017: Installation SRF Gun, 5 cell, laser and beam dump in RHIC May-Jul 2017: Commissioning Cryo system and LEReC RF system Jul - Sept 2017:LEReC with beam commissioning Stable CW operation at 1 mA average current full LEReC systems Oct 2017:Commissioning with Ion beam LEReC timeline commissioning milestones

July LEReC required critical components have been already installed in BLDG 912 and are under commissioning 704 MHz SRF Gun is under commissioning towards beam in BLDG 912 since June 2014 Gun reaches CW 2 MV without cathode stalk insertion Mulitpacting problems in the cathode stalk. Copper plated stalk will be tested shortly. A new photocathode stalk will be delivered in Nov. this year One cathode with QE=2E-3 was made for the beam test. All subsystems function well. Dark current has been observed during first beam test and measured. There is no sign of cavity degradation due to operating with photo-cathode. The cavity performance improves after every test. New transport cart and cathode stalk should assure CW, high current performance. We conduct commissioning of LEReC critical components in BLDG 912 in order to reduce time and mitigate risks before commissioning starts at RHIC IP 2. Summary