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SLAC SC Linac Installation Mini-Workshop

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Bldgs. 52 & 53 (SLAC)

Bldgs. 52 & 53

SLAC
Mattia Checchin (SLAC), Qiong Wu (BNL)
Qiong Wu
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1.3 GHz SC Linac

 

1. LCLS-II Overview

·       Earthquake has no affect on the operation. Only very short unstable time for beam signal.

·       No really dark period, as the normal conducting linac can fill

·       Float is 33 months, and still need this as much

·       CD3A/B/C are very helpful. More than half of the cost in material were purchased in these phases.

 

2. LCLS-II Operation

·       3% of the cavities are not operational. All can be fixed by warm up and cool back down. New issues all from LLRF.

·       Cavity turned off by shut down RF usually. If the effect to beam is large, then detuned by 80 -120 kHz.

·       Cool down valves caused Microphonics.

·       Current insulation leak in one module needs investigation. Need to open CM before knowing the location and leak level.

·       By MP conditioning in 2-3 hours each, the cavities can go up to 20MV/m. Cavities with high field emission (FE) are not MP conditioned to avoid increase in FE.

·       The cryo plant is at limit if running at 4.3 GeV beam energy. Total load at 2K is 3.5kW – 4kW

·       The GUI for control system is developed by LCLS2 physics group

·       No beam loss in straight SRF linac, but beam loss in interfaces. Especially change in aperture. One incident of beam loss generated a high radiation area.

·       No CM below 16 MV/m after MP conditioning. Some cannot reach 20 because other limitations.

 

3. LCLS-II HE Cryomodule Installation

·       Standardize the interconnects is VERY important

·       Must finish sealing the ceiling before cryomodule goes underneath. The helium guard plate should be on before cryomodules arrive. Plan well of the area before put the cryomodule in.

·       Using cryogenic pipes from the same batch helps improve the quality of welding. Welders trained and continue to weld by same group. These details optimize efficiency.

·       The cryomodules are 27” above ground for cleanroom installation. Ergonomic experts training needed.

·       Weldings of the pipes are done first, then installing Beam Line Absorbers. The BLA wants to go from pump downstream, the welding like to go from purging to pump. Well planning is needed.

·       Insulation vacuum needs 2-3 months to pump down.

·       No valve between return line and cryomodule 2K distribution.

·       1 week for getting cryomodules in place, another week for installation of the cryomodule interface pieces.

·       Interface beam pipe is connected under temporary cleanroom cart. Due to cryomodule very close to the wall, the person working between the module and the wall has no line of sight while connecting flanges. Mirrors were used.

 

4. LCLS-II HE High Power RF Installation

·       Not worried about vibration in waveguide, dampers and clamps used

·       No cleanroom work for waveguide

·       SSA in tunnel does not worth it. Highly recommend free access to the SSA units and good tunnel temperature control.

·       1 month for preparing all HL and LL hardware work. 2 weeks for cryomodule in place + interface installation. They overlap.

 

5. Installation Tracking and Reporting (Business Intelligence)

·       Tableau dashboard can be manipulated by tech managers

·       Integrated various documents generated from different project software by using Micro Soft Project

·       MS Project updated weekly

·       Tableau dashboard show milestone delay. If one area is triggered, it automatically shows on all affected sections.

·       Dashboard show CV and SV directly from EVMS.

·       Managers pull analysis charts themselves as needed.

·       Administrative decision to use Tableau, and appreciated over the project.

 

6. Removal of Legacy Equipment

·       Every equipment is labeled before working on removal. Removal in red, save in green, also some equipment to be abandon in place for future use taped off.

·       Clear documentation improves efficiency and avoid mistakes.

·       Accident example: Mercury sensors broke by contractor, mercury dropped down to radiative area. Solve immediately.

 

 

 

 

 

2856 NC Linac

 

PSI can only take 5nC, due to wakefield, both trans and longi. FACET can do 2nC.

No circulator needed

Prototype fabricated by company in Idaho, length is 1m. Standing wave. $4000/half slice,

 

 

 

 

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