S2 Progress Report for EC H. Padamsee and Tom Himel For the S2 Task Force

Review S2 Goals (1) Review TRC R2 recommended tests and revise list Determine generic lessons learned from the operation of TTF and other SRF based accelerators –How are these lessons applicable for S2 tests and ILC Assess number of RF units needed for planned activities Assess if beam is needed See what assemblies and tests are presently done or planned at – FLASH (TTF-II), SMTF STF Assess their timelines –compare with S0, S1, TDR Evaluate impact of XFEL plans on S2 needs

Review S2 Goals (2) (Relationship to Industrialization/Production Scenarios) The Plan should show how the transitions from proof-of-principle to the S2 Milestone and to the start of main linac production should be accomplished. –Look at how previous high tech projects have been industrialized –Make model (s) for the cavity/cryomodule industrialization plan(s) to prepare for ILC construction –Work backward to determine where R&D needs to be over intervening years between now and construction –Do we need a phase 2 (longer string test of many RF Units)

Discuss Tests Needed Examples Under Discussion Tests with < 1 RF Unit –(e.g. at cryomodule test stand) Tests with 1 RF Unit Tests with a few RF Units Tests with N >> 1 RF Units

Example Tests With < 1 RF Unit e.g. at cryomodule test stand Test reliability of components. –Of particular concern are components with long MTTR such as tuners, piezos, and couplers. Use ILC design piezos, tuners, HOM, and cryomodule Measure dark current in cryomodules –cryo load –radiation Important for electronics and personnel in tunnel with RF on. Check for cavity and quad vibration due to use of piezo tuners

Test transportability of cryomodules Test compatibility of cryomodules from mixing those of different regions Try a dirty vent on some cryomodules and evaluate extent of damage and recovery Do above with a fast acting valve to see effects both of valve and of the dirty vent Provide a test bed for evolving industrially produced cryomodules. –desire to test preproduction cryomodules before full production released Tests Which Can Be Done With <1 RF Unit (con’t) e.g. at cryomodule test stand(s)

One RF Unit Tests (y = with beam) Demonstrate that we can make an RF unit to ILC spec for gradient, Q, dark current –Evaluate cavity quench, coupler breakdown rates and recovery times at 31.5 MV/m for long-term operation –Check static and dynamic cryo heat loads at spec (y) –Are these commensurate with the operational expectations Test RF fault recognition and recovery software (y) –Insure that adequate instrumentation is available to sense likely faults. (coupler breakdowns, cavity quench, broken tuner motor, broken coupler motor, defective sensor… Check for trapped HOMs including between the cavities using final cavity spacing Check beam phase and energy stability (y) Provide an RF unit for LLRF tests for several years (y) Determine capability of LLRF, tuners, and couplers to deal with gradient spread in cryomodules..how much spread can be dealt with?

Tests Needing More than One RF Unit Measure dark current –effects cryo load –how much dark current is accelerated/captured from module to module –How much radiation Important for electronics and personnel in tunnel with RF on. Check cryo control (maintain liquid levels, feedback time response etc.) and vibrations due to cryogen flows Mock up actual tunnel layout to explore installation, maintenance, and repair issues prior to large scale construction of ILC –could influence civil designs

Tests needing N >> 1 RF Units (probably not practical) Check for emittance growth due to cavity misalignments Check for emittance growth before and after DFS steering

Next Steps Which system tests are done at TTF, SNS… –(e.g next slide) –What have we learned? What tests from previous lists can be done at TTF-II/FLASH? –Start a dialog between S2 and TTF-II to make a list –List tests that must be done elsewhere Compare time lines

Down time weeks Total downtime: h (13%) h (71%) 24.2 h (7%) 20.5 h (6%) 9 h (2%) 17 h (5%) 10 h (3%) 4.2 h (1%) 1.5 h (<1%) 1 h (<1%) 0.8 h (<1%) 10.3 h (3%) 7.6 h (2%) Klystrons / modulators: 71% LLRF: 7% Photonline: 5% Laser: 6% Magnets: 2% Controls: 3% Protection: 2% Other: 3% Water: 1% Klystrons / modulators is the sum of both plus waveguides, pre-amplifier, interlocks…. We urgently have to detail this; about 50% was one single event (bouncer circ. capacitor)

Do we need a longer string test (phase 2)? (Relationship to Industrialization/Production Scenarios) The Plan should show how the transitions from proof-of-principle to the S2 Milestone and to the start of main linac production should be accomplished. –Look at how previous high tech projects have been industrialized –Make model (s) for the cavity/cryomodule industrialization plan(s) to prepare for ILC construction –Work backward to determine where R&D needs to be over intervening years between now and construction

Examples Studied LEP-II SC system evolution –350 MHz, Nb-Cu Technology –288 cavities, 500 meters –Total 72 modules over 6 years –3 years 4 modules per year –Start-up 12 modules/year –Final rate 25 modules/year LHC evolution –1250 magnet modules, 15 m long Need to compare with XFEL scenario as it develops >120 modules 6 modules tested in TTF-II (string test)

12/ year 4/year 29/year 24/year 6 years total

Brief Remarks for LEP Lessons –4 modules installed in LEP for initial system tests with beam –Many lessons learned Couplers need to be improved pondermotive oscillations, controls Optimize RF distribution

LHC: R&D, Pre-Series and Production Phases, Total CM LHC Project Approval 1 m 10m 15 m LHC String Test 1 Pre- Series Series

R&D With Industry Phase Before LHC Approval Initial R&D with industry, 1991 – x 1.3m magnets/modules ordered from 5 firms 7 x 10 m long magnets/modules ordered from 4 firms LHC string test first reached design field in Dec 1994 –2 dipoles (10m) and 1 quadrupole LHC approved in Dec 1994 LHC String test 1 complete Jan 1999 (4 year test) String test 2/1, 3 D (15m), 1Q, 98 – 01 String test 2/2, 6 D (15 m), 1 Q,

LHC String Test The String has been an invaluable test-bed for LHC systems such as cooling, vacuum and magnet protection and has also served as a training ground for the String team and operators The String began operation in December 1994, just before the … LHC project was approved. Since then five experimental runs have been carried-out. The first runs were aimed at validating the design choices for the individual systems. The emphasis then shifted towards optimisation of the design, while later experiments were designed to highlight any weak points through artificially induced fatigue on components and the interconnections between them.

Many Scenarios Still Under Discussion in S2 One Possible Example An Evolutionary Picture Learning : Stage 0 –1 RF unit Stage 1: 1 – 2 RF Units –Reach spec –Make modules regionally compatible Stage 2 : Many RF units together in one location Need to examine each relative to ILC timeline, XFEL plans & timeline,

N= 1 - 2

Conclusions We are defining goals for S2 –Phase 1, carry out needed RF unit tests, keep it small to have minimal impact on funding decision –Phase 2 longer string of RF units to get good statistics on cavities, cryomodules, RF, LLRF…(industrial?) After approval ? We try to make S2.1 consistent with S0, S1 –Number of cavities, timeline… We need to adapt the plan to available funding –phase 1 and 2 What is clear so far: –It is a large effort –Parts of Phase 1 can be done in TTF-II (define how much) Push for Plan formulation by Valencia We need your advice on our phased approach !