SRF COLLABORATION MEETING MAY.2016 ESS MEDIUM BETA CAVITY MANUFACTURING CEA Saclay/ESS ECCTD WU Cavités | Enrico Cenni

| PAGE 2 Cavity fabrication Heat treatment BCP OUTLINE

FIELD FLATNESS, FREQUENCY AND LENGTH | PAGE 3 Acceptance measures at CEA P01P02 Length [mm] π-mode [MHz] Field flatness 57%89% ΔL from computed [mm] ΔF from computed [ kHZ ] ΔL from target [mm] ΔF from target [ kHZ ] ΔF/ΔL Cavity tuning sensitivity 211 KHz/mm Trimming and EB welding proved to be reliable and controllable. Both cavity are delivered with frequencies and length close to the computed tuning curve More information on TAC13

CAVITIES STATUS (5/2016) P01P02 Tuning and FF at 95%Field flatness 89% at delivery BCP 200µmBCP 50µm HPRImproving BCP set up 1 st Vertical test 2 nd Vertical test (fast cooling) 4K/min Heat treatment (600°C x 10hours)

HOM AND FIELD FLATNESS AT DELIVERY | PAGE 5 P01 P02

COMPONENTS AND CAVITIES 2 medium beta cavities manufactured. All Dumbbells and End groups completed with RF measure and ready for trimming Helium tank prepared for welding. | PAGE 6

RF MEASURES 0.5MHz RF connector Antenna Upper plate (iris side) Lower plate (equator) side) Dumbbells Half cells 0.5MHz

SHAPE CONTROL | PAGE 8 3D CMM result on a central half cell, red +0.15mm, purple -0.15mm. Scheme of average deformation observed on central half cell not in scale. Length difference between simulated and measured values on central group (red) and end group (blue) halfcells, each bin has 0.02mm width. Laser tracking 3D measure performed at CEA

| PAGE 9 HEAT TREATMENT Heat treatment performed at 600°C for 10 hours at Zanon (same oven as XFEL) Blank run before the cavity treatment Niobium sample inserted into the oven, it followed the same treatment as the cavity. A reference sample was kept outside as reference. Sample analysis is ON GOING

Titanium Alumina 99% Stainless steel

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TEMPERATURE | PAGE 13

AFTER 40 MIN AT 600°C | PAGE 14

RGA | PAGE 15

BCP | PAGE 16 We are working on the BCP process in order to optimize it. Due to administrative regulation we use a mixture 1:1:2.4 (HF/HNO/HPO)

17 CHEMICAL TREATMENT (BCP) WITH ACID MIXTURE 1:1:2.4 Acid flow Rinsing after the BCP Automatic BCP treatment ~3°C/hour Acid flow

18 TEST IN VERTICAL CRYOSTAT Q-DISEASE  Hypothesis of the Q-disease: high hydrogen concentration Example of the SPL cavity cured after the heat treatment for H2 degassing

| PAGE 19 Acid tank temperature Top of the cavity Acid tank temperature Bottom of the cavity We installed temperature sensors on the cavity surface and monitor the temperature during BCP process (designed a LabView interface for continuous monitoring). Acid was cooled at 10°C the cavity was at room temperature (17°C°).

FIELD FLATNESS AND PI-MODE FREQUENCY | PAGE 20 ΔFπ~ 300KHz expected 358KHz (for 100μm etching) with uniform etching. It is close to computation results. Decrease of 3% in FF after BCP, we are investigating the cause. Fπ=703.9  703.6MHz

DSM Irfu Commissariat à l’énergie atomique et aux énergies alternatives Centre de Saclay | Gif-sur-Yvette Cedex T. +33 (0) xx xx | F. +33 (0) Etablissement public à caractère industriel et commercial | RCS Paris B | PAGE 21 THANK YOU FOR THE ATTENTION

MEDIUM BETA CAVITY | PAGE 22 Parameter Value Geometrical beta -  geom 0.67 Frequency [MHz] Number of cells6 Operating temperature [K]2 Maximum surface field in operation [MV/m]44 Nominal Accelerating gradient E acc [MV/m] at  opt 16.7 Accelerating length L acc = (n cell.  geom. /2) [m] Q 0 at nominal gradient> Cavity dynamic heat load [W]4,9 Q ext Cell to cell coupling  [%] 1.22  and 5  /6 (or 4  /5) mode separation [MHz] 0.54 E pk /E acc 2.36 B pk /E acc [mT/(MV/m)]4.79 Maximum r/Q [  ] at  opt 394 Optimum beta  opt G [  ] prototypes will be built, 4 will installed in the cryomodule 2 cell shapes (central cells and end groups)

| PAGE 23 Medium beta cavity, computation of Slater perturbation on π/6 mode for HOM 3rd passband.

AFTER 40 MIN AT 600°C | PAGE 24