LCLS-II cryomodule alignment

2 Wednesday meeting, 6/17/2015 Topics Alignment of Components inside the CM Tunnel Network Tolerances LCLS-II cryomodule alignment workshop Friday May 22 nd at FNAL

3 Mechanical design – images from the CAD model (from Yuriy Orlov) Wednesday meeting, 6/17/ ” vacuum vessel with 8” vacuum releave valve. 2- cryomodule adjustment supports Sliding interconnection Bellow. 8- coupler ports with power couplers and vacuum manifold. Instrumentation ports & magnet CL Flange.

4 Mechanical design – images from the CAD model (from Yuriy Orlov) Wednesday meeting, 6/17/2015 Cryomodule length: ~12.3m 3 supports for cold mass (1-fix. and 2-sld.) 300 mm –ID, 12m long tube, as backbone for cavity string, piping system and thermal shielding cell dressed elliptical SRF cavities(with mag. Shielding) + 1-BPM +1- SC splitable quadrupole + 2 Gate valves. (one of the each end of Cavity string) Piping system of Cryomodule. 50K aluminum shielding with 30 layers of MLI insulation around cold mass.

5 BPM & QUAD Wednesday meeting, 6/17/2015

6 Cavity alignment (from Virgil Bocean) Wednesday meeting, 6/17/2015 The RF group will provide the mechanical to electrical center offsets for each cavity with respect to the cavity end flanges Offsets of 300µm between electrical and mechanical centers have been found. Tolerance of individual cell?

7 String Alignment Wednesday meeting, 6/17/2015 Alignment in warm conditions Different offsets between Cavities (x=0.24mm; y=1.97mm) and Quad (x= 0.00mm; y=1.97mm) Tolerance: 150µm, wavelength 13m

8 Cold vs. Warm repeatability Wednesday meeting, 6/17/2015

9 String Alignment: Cold vs. warm Wednesday meeting, 6/17/2015 Z position changes of up to 17mm depending on distance to main support. Offsets are based on DESY numbers. Tolerance: +/-0.175mm RMS, 3m pattern (the support posts seem to be stable)

10 Cold mass vs. vacuum vessel Wednesday meeting, 6/17/2015 Support posts are removed during installation, repeatability needs to be determined No possibility to check movements after insertion into vacuum Vessel.

11 Cold mass vs. vacuum vessel Wednesday meeting, 6/17/2015 Fiducial on gate valve and support posts will be transferred to vacuum vessel fiducials Tolerance: <100µm (picture curtesy Tom Peterson)

12 QC at SLAC after transport Wednesday meeting, 6/17/2015 Same measurements as cold mass vs. vacuum vessel, gate valve fiducials and support posts relative to vacuum vessel fiducials. DESY reported up to 300µm discrepancies. Acceptance tolerances have to be specified. Tolerance: 0.3mm RMS, 3m pattern (I assume that the support posts don’t move)

13 Tunnel Alignment Wednesday meeting, 6/17/2015 Local alignment of CM: 0.05mm RMS, every 15m Alignment network: 0.3mm RMS at 100m distance. Tunnel is narrow -> refraction will affect measurements. Position [m] Coordinate change [µm]

14 Summary of Alignment Tolerances Wednesday meeting, 6/17/2015 Different aspects of error budget stack up: Relative alignment of cavities to string: +/-0.075mm RMS; every 1.3m Cold/warm uncertainty: +/-0.175mm RMS, 3m pattern (the support posts seem to be stable) Transport shifts: 0.3mm RMS, 3m pattern (I assume that the support posts don’t move) Single cavity to cavity assembly: 0.3mm RMS?, every ~0.15m Alignment of components in the tunnel: 0.05mm RMS, every 13m Alignment network: 0.3mm RMS, ~100m wavelength