Pierre Bosland

23RD OF JUNE 2015

ESS CAVITIES INTERFACES

223RD OF JUNE 2015

Cavities lifecycle

Cavity lifecycle after factory acceptance:

1. Transport in a dedicated box to vertical test stand: cavity equipped for test in vertical cryostat with

• The final RF pickup mounted on the cavity• The b=1 antenna mounted• Valve adapted for cold RF tests in superfluid helium.

2. Test in vertical cryostat: interfaces with cryostat and with handling tools

3. Transport to Saclay (same box as for 1)

4. Acceptance stand at Saclay

5. Assembly in cryomodule

323RD OF JUNE 2015

423RD OF JUNE 2015

 The cavity production is under the full responsibility of the LASA/STFC.

The factory acceptance criteria are established by LASA/STFC in agreement with ESS and the factory acceptance are under the responsibility of LASA/STFC.

The RFA (Ready For Assembly) acceptance criteria are established in a common agreement between CEA and ESS/LASA/STFC. The RFA acceptance tests (and controls: QC ?) will be performed by CEA.

The RFA acceptance of each cavity before assembly will be under the responsibility of ESS.

The transfer of the cavities ownership to ESS is effective after the RFA acceptance of the cavities.

Non conformities will be managed following a policy on which each party shall agree upon.

Acceptance and transfer of ownership PROPOSAL

Date for criteria agreement to be defined now!

523RD OF JUNE 2015

Cavities interfaces & requirements

Cavity physical interfaces before assembly in the cryomodule:

1. Beam flanges (closed by a blank flange + valve)

2. Power coupler flange (closed by a blank flange + b=1 antenna)

3. Pickup mounted on the cavity: RF pickup connector

4. Support of the cavity in the cryomodule (interfaces for rods fixations)

5. Magnetic shielding

6. Cold tuning system

7. Handling tools

8. Alignment tools interfaces

9. Cryogenic pipes: flange of the cooling helium pipe (to be suppressed by a

welded tube or not ?) + welded tube to the 2 phases tube above the

helium tank.

623RD OF JUNE 2015

BEAM FLANGES & « TUNER RING »

Vacuum tightness Alignement tools and reference Blocking fixtures

723RD OF JUNE 2015

POWER COUPLER PORT

Vacuum tigthness External coupling Qext (height & position %

cell iris)

54 56 58 60 62 64 66 683.0E+05

4.0E+05

5.0E+05

6.0E+05

7.0E+05

8.0E+05

9.0E+05

1.0E+06Qext

high beta

medium beta

distance axis-antenna tip D (in mm)

The Qext sensitivity calculated with HFSS gives:•Medium beta cavity: D=61,26mm for Qext =7,5e5•High beta cavity: D=64,41mm for Qext =7,6e5

D

47

70

Rext = 50

Rint = 21.74

35

Rcone (without filet) = 28

Hcone = 50

Rfilet-tip = 3

Rfilet-base = 8

823RD OF JUNE 2015

PICK-UP ANTENNA

RF connector at 90°

Cavity beam tube

Alu gasket

Pick-up antenna

Pick-up port

• 30 units ordered • Designed to transmit 30 dBm

Transmitted power required by LLRF: Pt > 20 dBm at nominal gradient

923RD OF JUNE 2015

COLD TUNING SYSTEM

• Amplitude slow tuner: +/- 3 mm• Amplitude fast tuner (piezo): 3 µm

    Medium beta  High betaNiobium thickness mm 4 3.6Tank thickness mm 5 5Lorentz Force Detuning coef. KL fixed ends Hz/(MV/

m)²)- 0.735 -0.36

Lorentz Force Detuning coef. KL free ends Hz/(MV/m)²

-23.35 -8.9

Cavity stiffness kN/mm 1.286 2.59Tuning sensitivity Df/Dz kHz/mm 214.8 197

1023RD OF JUNE 2015

MULTILAYER INSULATION

- Between helium tank and magnetic shield

- Detailed design not yet finalized

1123RD OF JUNE 2015

MAGNETIC SHIELDING

1223RD OF JUNE 2015

CAVITY SUPPORTING SYSTEM IN THE CRYOMODULE

1323RD OF JUNE 2015

HELIUM SUPPLY AND RETURN

He return (welded)

He supply

• Pressure test to be established

1423RD OF JUNE 2015

CAVITY HANDLING TOOLS

Transport, assembly and rotation

Unpacking and handling horizontally

Lifting

Horizontal support and rotation for visual inspection

Wheels

1523RD OF JUNE 2015

Cavity functional interface requirements (see DOORS):

1. F = 704,42 MHz at 2K

2. Acceptance F = XXX at the acceptance conditions to be defined

3. Eacc= 16,7MV/m (Mb) Eacc= 19,9MV/m (Hb) <= cryomodule nominal

4. Dangerous HOM frequencies: 5MHz away from integer multiples of the beam bunching frequencies

(n*352,21MHz)

5. Power coupler Qext : 5,9E5 < M < 8 5 b E & 6,6E5 < H < 7,6 5b E - see technical notes for Mb and

Hb cavity couplers.

6. R/Q = 395 at bopt => Pmax close to 900kW for medium beta cavities to get the needed voltage . Need

of a high R/Q value!

7. Pickup antenna Qt – no issue - requirement 20dBm at the pickup connector at the nominal field

8. Lorentz force detuning: 3µm max deformation with piezo stacks

9. PS = 1,04barg + V max LHe = 48 liters => article 3.3 according to PED

10. …

SOME REQUIREMENTS L4