HL-LHC Crab Cavity Review Debriefing

Comments from LARP

June 30, 2014

Recommendation 1

We suggest that two cavity designs be selected for the beam tests at SPS. These cavities should incorporate complementary different HOM coupler configurations, as were presented for:

• Double Quarter Wave (DQW) design proposed by Brookhaven National Laboratory (BNL) with Coaxial HOM Couplers, and• RF Dipole (RFD) design proposed by Old Dominion

University (ODU) with a waveguide HOM Coupler.

N. 1 - Action

• The third cavity design is on hold, as recommended.

• More at point 4.

Recommendation n. 2We suggest that further development and the beam test preparation be prioritized with the DQW design because the engineering design work appears to be better advanced to meet a very limited preparation time.

However, we encourage the RFD cavity development to be continued with strengthening the waveguide HOM Coupler development. We note that either the DQW or the RFD could be tested first in SPS, depending on the readiness of the cavity and CM preparation.

N. 2 - Action• We propose to continue pursuing the two cavity designs.

HOWEVER we propose to use coaxial mode dampers in both designs. This is different from the recommendation.

• This is motivated by the tight timeline which would make a timely completion of the waveguide solution very risky.

• This is supported by the calculations of the power in the HOMs which show that a coaxial system should be able to handle the projected power (today). This work was presented at the review.

• We propose to continue both candidate designs at full speed. When resource conflicts arise, we will give priority to the DQW design, as long as it remains the most likely to be completed in time.

Recommendation n. 3

The prototype cavity and the cryomodule fabrication should be started as soon as possible in order to cold test at SM18, prior to the SPS beam test expected in 2016 – 2017.

N.3 Response

• Agreed. • This recommendation reinforces the plan

already in place.

The Lancaster University (LU) group is recommended to work on further CC development and test programs including HOM couplers, cryomodule development work, as well as CC SPS beam tests.

Recommendation n. 4

N.4 - Response• We are integrating the LU team in the ongoing

activities of the two candidate designs• Efforts are underway to improve the efficiency of

this integration• Due to the maturity of the two designs, the most

impact is expected on the CM design– Validation of EM modeling results of both cavities is

still very important• Contributions from LU are coordinated by CERN

Recommendation n. 5

A clear and plausible plan to realize the SPS beam tests within the limited time should be developed with strong leadership from the project management.

N. 5 - Response• The plan prepared at CERN was presented at the review

– Alick’s talk– Now tracked and updated for progress

Identified Some Action Items – improving communication:• Reorganization of the WP4 website improved/easier access and

sharing of information among the various tasks.• A common meeting for both designs initiated immediately after

the cavity interfaces are fixed.• As necessary a WP4 meeting within CERN for inter-

communication between tasks.

Ongoing Action Items• Field emission trajectories with HOM couplers → perform

use SLAC codes• Benchmark between codes to verify HOM damping → UK will

help + CERN• Minimize design variations between the cryomodules → EN-

MME• Show plausible concept for both crossing planes →

Immediately after MFG kick-off meeting• Magnetic shielding (inside He-vessel + outer vacuum vessel)

→ STFC + EN-MME• Cavity-coupler fabrication tolerances → Under study

Cavity Design Status

• Both models in final detailing• Preparing release package– Next slide

• CERN completed system requirement document with all annexes

• Preparing for Production Readiness (AKA kickoff) meeting at CERN (September?)

Release to NioWave

• Release process defined and distributed• DQW in final step of process– Final check at FNAL + release

• 3D model for DQW endorsed by CERN– Now providing details for fabrication drawings

• 3D model for RFD is under checking at CERN– Next step is final check at FNAL

CC System – from CERN ESWP4

Crab cavities

SPS

Cryomodule

Vacuum vessel

External supports

Jumper connection

Internal assembly

Cryogenic circuits

Low-pressure helium pumping collector

2 K helium supply

LN2 auxiliary cooling lines

Pressure relief circuits

Supports Thermal shield Magnetic shield

Dressed cavities

Bare cavities with interfaces

Bare cavities

Interface components

Tuning system Helium vessel HOM couplers

Instrumentation Vacuum valves

LARP

LARP Plan for FY15• Preparing budget request including

– 2 cavities of each kind with He vessels• Through SBIR as much as possible

– All processing needed to qualify all cavities• Vertical tests only• In compliance with EU/CERN norms

– HOM filters for all cavities

• Max funds available in FY15 do not include tuning systems– Will include in funding request in FY16 (from Oct. 1, 2015)

• Could be late – can we manage?– BIG uncertainty about what will be included in SBIR

• Will clarify this week

• FY15 planning will be discussed by Alex at CERN next week

Major upcoming events

• Final release of both cavities – imminent• Start of production at Niowave – after release– Test materials as required in ES.– Preparation of detailed production drawings.

• CERN visit to Niowave – August 2014• Production Readiness kickoff meeting at CERN –

September 2014– Production start

• HL-LHC collaboration meeting – Nov 2014