All Metal Gate Valve from VAT Tug Arkan December 12, 2014

Cleanliness for particle free UHV standard VAT: Cleaned to ISO6 (Class 1000) standards at the vendor Closed during shipping Flanges are covered with some kind of cover plates Double bagged in the cleanroom CAF Cleanroom Group: Move the valve from production floor to Class 10 (ISO 4) cleanroom Clean the valve to Class 10 (ISO4) standard by blowing with ionized nitrogen and monitoring with a particle counter before assembly

Copper plated inside for the inner workings of the valve mechanism (not special RF liner) Gate valve fully open in its holder fixture at the cleanroom

Upstream end gate valve (CM2) For LCLS-II prototype cavities there will be a spacer flange assembled between the gate valve and cavity flange

Downstream end gate valve (CM2) CM2: Magnet + BPM + Spool piece + Downstream end gate valve LCLS2: BPM + Magnet Spool Piece + Downstream end gate valve

LCLS-II prototype module cavity string

3.9GHz cavity string Zero length reducer: from NW78 to NW40 aluminum diamond seal

Upstream end gate valve cold mass interface A titanium gate valve holder is tack welded to the helium vessel body of Cav#1 This holder is used to ensure that the weight of the gate valve (~50 lbs) doesn’t disturb the RF properties of the Cav#1

Downstream end gate valve cold mass interface Gate valves are inside the 5K shield attached to the Cav#1 and magnet spool piece for LCLS-II. No external thermal intercepts for the valves.

LCLS-II Gate Valves from VAT Cleaned to Class 1000 standards and double bagged Magnetic permeability class 1 (µr ≤ 1.05) Flanges are made of 316L DESY required thermal degasification at 950°C for the valve body and the bonnet but not the mechanism components of valve 472XX-XE01-ADD1. Same for LCLS-II

Quality Control & Acceptance This valve is shipped double bagged and cleaned to ISO6 standards from VAT. We will open the bags and move the VAT valve to ISO4 cleanroom Visual check, open the flange covers and inspect for scratches and nicks Follow the opening and cleaning procedure of the valve and record the particle counts Follow the travelers to ensure that the stainless steel assembly hardware is assembled properly during string assembly to eliminate galling potentials