CEBAF Accelerator Status Arne Freyberger Operations Department Accelerator

CEBAF Accelerator Status Arne Freyberger Operations Department Accelerator Division CLAS Fall 2017 Meeting

Availability Challenges Range of CEBAF Availability during 6 Ge. V Operations CLAS Fall 2017 Mtg 2 2

CEBAF System Availability • Weekly availability reviews at the weekly scheduling meeting • Early identification of issues • Monthly availability report • Presented and discussed on the first Friday of a new month at the daily 8 am meeting • Look for trends • Increased statistics for better information • Annual availability review is used to set priority for support groups annual work plan (AWP). • Feb. 2017 shown • A good month CLAS Fall 2017 Mtg 3

DTM • Tracks all downtime events • Downtime: Period longer than 5 minutes • Requires manual entry by operator Data quality may not be the top priority when things are not going well • Operability reviews and presents every Wednesday Useful interpretation of this data requires that system owners help Operability in QA the data. • Dealing with system downtime during non-beam operations not trivial • Dealing with stops/starts of program not trivial • Downtimes that result in program and/or schedule change may not be correctly tracked CLAS Fall 2017 Mtg 4

Availability Data: DTM • CLAS Fall 2017 Mtg 5

It’s not personal, it’s data CLAS Fall 2017 Mtg 6

System Availability CLAS Fall 2017 Mtg 7

System MTBF (Large # is good) End of life WTF!!!!!! CLAS Fall 2017 Mtg 8

System MTTR (Small # is good) CLAS Fall 2017 Mtg 9

Cryogenics • Data highly skewed by significant events that resulted in programmatic change • MTBF mostly due to CHL 1 ->SC 1 faults, classic end of life. CLAS Fall 2017 Mtg 10

RF • MTBF: about two events per day • MTTR: less than 1 h, good but that’s two derailments per day. • Would better training of operators improve MTTR even more? Improved controls? CLAS Fall 2017 Mtg 11

CEBAF Performance Plan • Define the performance goals Availability/Reliability Beam Parameters (emittance, energy spread, bunch charge, beam energy) Peak Conditions (Hall multiplicity, operating weeks, …) • Perform gap analysis to identify where present CEBAF performance does not achieve the performance goals • Develop a plan to close the gaps CLAS Fall 2017 Mtg 12

CEBAF Performance Goals CLAS Fall 2017 Mtg 13 13

CEBAF 20 year view CLAS Fall 2017 Mtg 14

Critical Spares Top Priority 1. Spring 2014: ZA magnet coil and vacuum failure; 3 week interruption to replace damaged coil and repair the vacuum chamber. This failure consumed the existing spare coil; the next failure will take much longer for repair and recovery. 2. Spring 2015: Cold compressor 4 failure in 2 K cold-box, SC 1; No spare at JLab, consumed the SNS cold compressor spare. Program change required: half design energy after 5 week down. 3. Fall 2015: YR coil on 3 -pass extraction generated a spontaneous leak. No 3 pass program for FY 16, repaired Summer 2016, consumed a YR coil spare. Required Hall-A DVCS experiment to re-arrange its run plan. 4. Fall 2016: Arc 7 box supply failure, no spare, program change required: to single hall operation until supply repaired. 5. Fall 2016: 5 th pass separator vacuum leak, program change required, could not support 5 th pass beam to Hall-A simultaneously with 5. 5 pass beam to Hall-D. 6. Spring 2017: Cold compressor 5 failure in 2 K cold-box, SC 1; on-going root cause investigation, might be repairable. Scheduled program terminated. CLAS Fall 2017 Mtg 15

Energy Gap and Plan Energy Gap: • Presently CEBAF cannot support design energy (FY 17/FY 18 operations at 4% below design) • Annual gradient loss exceeds the gain from one C 50/year One C 50/year insufficient to maintain energy reach; gap is growing! Energy Plan: • C 75 Upgrade: replace the C 20 cavities with high current 5 -cell cavities Re-use as much of the cryomodule as possible • Total cost in terms of MV/$ lower than C 50 or C 100 options Upgrade LLRF to digital controls (similar to C 100) Target specifications: • Gradient: 18. 5 MV/m • Q 0 > 8 e 9 • Upgrade warm region vacuum and clean (SRF quality processing) all warm vacuum regions two warm girders/year (continues to end of 12 Ge. V/era) • Upgrade analog LLRF with digital LLRF in all zones two zones per year (continues to end of 12 Ge. V era) CLAS Fall 2017 Mtg 16

Energy Gap and Plan (C 75 Upgrades) Proposed path to design energy (1090 Me. V/linac) • Comparable to C 50 program post hurricane Isabel • If annual degradation is mitigated: might achieve 1090 Me. V/linac by FY 21 and with fewer C 75 modules CLAS Fall 2017 Mtg 17 17

Preliminary Performance Plan M&S Cost Estimate C 75 s C 100 -Refurbs Preliminary • Near term goal is to close the gaps by FY 23 • Plan emphasizes improving CEBAF availability/reliability first: • Energy Reach second • Operating at optimal weeks third • All dollar values in FY 17 direct costs 18 CLAS Fall 2017 Mtg 18

July 27 2017: CHL 1 Event • Modules that warmed above 50 K require a thermal cycle to room temperature and a controlled cool-down to 4 K • All the modules in these plots had temperature excursions above 50 K (or were already at room temperature for maintenance. • Significant He contamination and loss of inventory. • As of today all modules, except one, are full of LHe and @ 4 K. • This remaining module will be cooled and filled during the transition to 2 cryo plants CLAS Fall 2017 Mtg 19

12 Ge. V CEBAF Beam Parameters e et ol bs O • At the request from Physics Division the beam parameter table created in 2001 for the 4 -6 Ge. V program is being updated to reflect 12 Ge. V CEBAF capabilities. • Please work with your APEL (Michael Tiefenback) in developing a table that will define the beam parameters appropriately for Hall-B experiments. CLAS Fall 2017 Mtg 20

4 -Hall Constraints • In order to deliver beam to all 4 -halls: At least one original end-station (A, B or C) must be on 5 th pass • The last 4 days in Dec. 2017 as published violate this rule. • Hall-B will be at 5 th pass for all of Dec. 2017 (unless Hall-D is offline) • Lower passes will be arrange in the Jan/Feb/Mar beam delivery End-station cryogenic load can exceed the ESR capacity • End-station magnet/target cool-downs must be carefully scheduled. • High power target operations in one or more halls must be carefully scheduled. CLAS Fall 2017 Mtg 21

The Good News • • • CHL 1 has been cleaned and is back in service: Presently maintaining CEBAF @ 4 K All 5 cold compressors in SC 1 have been operated up to 20% of operating value. Full SC 1 spin up and 2 K pump-down attempts (the first since March 10 th) will take place today. Once CEBAF is @ 2 K; assessment of the SRF gradient capabilities will take place. Transition from CHL 1 ->SC 1 ->CEBAF to 2 cryo-plants maintaining 2 linacs @2 K schedule for Nov. 12. RF assessment + Magnet soak continues through Thanksgiving Re-visiting Cryo configuration during down-times: CEBAF/Cryo will remain @2 K over Winter break Pro: Fewer transitions on aging 2 K cold-boxes Pro: Beam Operations can be extended to Dec. 21 (NPES schedule has Dec. 18 th) Con: Increased cost (power bill) SRF OPS has been producing field emission free cavities for LCLS-II; 7 out of 8 cavities FE free. 4 -Hall system (lasers, separators, operations) ready for integration and first 4 -hall operations. The CEBAF Performance Plan has been developed and reviewed. Presently working for Lab leadership to find funding opportunities. Funding for a new 2 K cold-box (replace SC 1) has been secured in FY 17. 3 -4 year effort, $8 M. CLAS Fall 2017 Mtg 22

Backup CLAS Fall 2017 Mtg 23

Downtime Count CLAS Fall 2017 Mtg 24

System Repair Time CLAS Fall 2017 Mtg 25

Optimizing 12 Ge. V Operations • • 26 Reliability/Availability Focus 4 -Hall Operations Improved Linac/Cryogenic procedures: Reduce risk of cryoplant contamination due to He connections/disconnections Linac LHe Pressure optimization Address end-of-life issues: • SRF C 20 Warm poly RF windows • SRF C 20/C 50 end-can O-rings Improve C 100 warm girder tolerance to radiation environment Identify and correct errant magnets West Arc to East Arc extension cable, allows for West Arc power supply to power East Arc magnets. Provides CEBAF the ability to support a full ABC program in the event of an East Arc box power supply failure. Energy Reach/Gradient Maintenance Linac energy setting: margin -> reliable operations Identify source of SRF Particulate • Cleaning/processing warm girder regions Improved tunnel vacuum procedures CLAS Fall 2017 Mtg 26

CEBAF Weeks of Operation Delivered 45 40 Optimal 35 30 20 Accelerator Shutdown # Weeks 25 15 10 5 0 FY 01 FY 02 FY 03 FY 04 FY 05 FY 06 FY 07 FY 08 FY 09 FY 10 FY 11 FY 12 FY 13 FY 14 FY 15 FY 16 FY 17 CLAS Fall 2017 Mtg 27

From 2012 S&T Presentation CLAS Fall 2017 Mtg 28

FY 17 Joule Metric • FY 17 first year of 12 Ge. V operations reporting DOE metrics • Beam operations for FY 17 complete, with the exception of a few days of restoration at the end of FY 17 (Sept 2017). • Measured Reliability 76. 3% • Exceeds our expectations of 65% • Below nominal DOE goal of 80% for all facilities CLAS Fall 2017 Mtg 29

Availability/Reliability Gap & Plan Availability/Reliability Gap: • Reliability and Availability inadequate for robust effective operations. • Critical system failures have forced program/schedule changes to almost every run period to date. Availability/Reliability Plan: • Purchase CEBAF and Cryogenic critical spares • Build and commission a new 2 K cold-box • Purchase System immediate needs Shore up the depleted spares • Purchase 6. 5 k. W and 13 k. W klystrons Address immediate obsolescence issues CLAS Fall 2017 Mtg 30

Operations Gap & Plan Operations Gap (Support 4 -Hall/optimal weeks): • Operator/Crew. Chief Staffing inadequate for 4 -hall operation Group is presently 4 heads below historical 6 Ge. V levels • Technical and MCC staffing is inadequate to support optimal weeks (37 weeks/year) • ESR capacity insufficient to support robust 4 -hall operations Operations Plan: • Increase staffing • Execute projects that will reduce time required for maintenance Spare warm girders Redundant CHL carbon beds Transition from 2 PSS certifications/year to 1 certification/year • Build a new ESR for robust 4 -hall operations CLAS Fall 2017 Mtg 31