Hydroformed Multi-Cell Cavities. Update Waldemar Singer, DESY Peter Kneisel, JLab

W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy Hydroformed at DESY and dressed with end tubes at Jlab 2-cell units It was proven that hydroformed single cells reached Eacc up to 40 MV/m after EP and up to 35 MV/m after BCP. Currently the work is concentrated on multi-cell and 9- cell cavities

First RF test of the hydroformed 2 cell unit 2H2 after post purification at 1200°C and 50µm BCP

Qo(Eacc) performance of the one of 2-cell hydroformed cavity. Typically after ca µm BCP or EP and baking reached Eacc=30-35 MV/m

Three 9-cell cavities from hydroformed at DESY units completed at E.ZANON (Z145, Z163 and Z164) Z145 One 9-cell cavity from hydroformed at DESY units completed at JLAB Z163 Z164 Z145 Four 9 - cell cavities available now W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy

Surface treatment at DESY: 40 mm BCP, 800 °C heat treatment, tuning; 170 mm EP, ethanol rinsing, 800 °C heat treatment; 48 mm EP, HPR, T = 2 K RF Performance: Z145 Individual cells have performance between 30 MV/m and 39 MV/m W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy

Z145 Cavity Z145, all RF tests Test 1: after 40 mm BCP, 800 °C, 170 mm EP, 800 °C; 48 mm EP Test 2: after add. baking at 120°C for 48 h Test 3: after new feedthroughs and HOM coupler antennas mounted Test 4: after add. 10 µm EP W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy

Denis Kostin, MHF-SL, DESY Hydroformed cavity Z145 is installed in module 3***/ACC1 in FLASH W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy Hydrof. Cav. Z145

Cavity Z163 Z163 in preparation at DESY. Final EP is foreseen. Status: 800°C annealed, tuned by new tuning procedure, main EP done W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy

Tuning of Z163 by radial deformation. Allows significant change of the frequency (few MHz) keeping the cavity length W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy

RF tests of three 3-cell units After BCP and post-purification at 1200°C for 3 hrs with titanium and subsequent BCP. The total material removal is ca. 250 µm. Z164 Three 3 cell units are tested individually at JLab W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy Cavity Z164

W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy Z164 first RF test after 50 µm BCP + HPR done at JLab. Limited by Q-drop at 26.4 MV/m, no quench. Next step is EP After completing at E. Zanon JLab tested the completed 9-cell cavity Z164

Top cell (tube top) (Tube bottom) Bottom cell T-map on 3-cell hydroformed cavities from spun+ flow formed tubes at E acc = 27 MV/m, (JLab) indicating several hot-spots in the equator area, mostly on the top cell. Poster THP043 LINAC08 Tube after spinning Cavity top inside surface Cavity bottom inside surface Good Eacc results, nevertheless the tubes can be made better Relation of Eacc to the tube fabrication method W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy

Centrifugal Barrel Polishing CBP at DESY EP or BCP in combination with CBP seems to be a most appropriate treatment for seamless cavities Inside surface after CBP More to Barrel Polishing: Talk of Charlie Cooper tomorrow

W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy

Last development: Tubes of Black Lab + WahChang supported by DESY. Heavily deformed billet, processed for fine grain structure Shaped by forward extrusion and flow-forming Black Lab. Long tube 1,3 GHz cells hydroformed at DESY from Black Lab tubes Completed at JLab 9-cell cavity. In preparation for test at JLab W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy

Conclusions Fabrication of the 9-cell cavities (3x3 units) of TESLA like shape by hydroforming is proven. Hydroformed 9-cell cavity installed in cryomodule is in FLASH operation (proof of principle is successful) W. Singer, P. Kneisel, TTC Meeting, February 28 - March , Milano, Italy