Report of the ILC-TRC Working Groupon

Technology, RF Power, and EnergyPerformance

Chris Adolphsen

International Linear Collider –Technical ReviewCommittee (ILC-TRC) Overview

History– Winter 2001: IFCA

Requests Second ILC-TRCReport (First Published in1995).

– Fall 2001: Working GroupsFormed.

– 2002: Working GroupsConvene Four Times toDefine Tasks, ReviewProgress and FormulateSummary.

– Jan. 2003: Complete Report

Organization– Chair: Gregory Loew (SLAC)

– Steering Committee• Reinhard Brinkmann (DESY)• Kaoru Yokoya (KEK)• Tor Raubenheimer (SLAC)• Gilbert Guignard (CERN)

– Working Groups• Technology, RF Power and Energy

Performance Assessments (Chair: DanielBoussard)

• Luminosity Performance Assessments(Chair: Gerry Dugan)

• Reliability, Availability, and Operability(Chairs: Nan Phinney, Ralph Pasquinelli)

Charge to the ILC-TRC

• To assess the present technical status of the four LC designs at hand,

TELSA, NLC/JLC-X, JLC-C and CLIC

and their potentials for meeting the advertised parameters at 500 GeVc.m. Use common criteria, definitions, computer codes, etc., for the

assessments.

• To assess the potential of each design for reaching higher energies

above 500 GeV c.m.

• To establish, for each design, the R&D work that remains to be donein the next few years.

• To suggest future areas of collaboration.

Contents of the Report

Not in the Report:

• Selection of ‘Best’ Design• Cost Comparisons• High Level Summary of

Strengths/Weaknesses of theDesigns

• Likelihoods that R&D Objectiveswill be Met

• Review of Electron-Electron orGamma-Gamma Options

Included in the Report (450 pages):

• Descriptions of the Four Machines at500 GeV c.m.– ‘Mega-tables’– Upgrade Paths to Higher Energies– Test Facilities and Other Project

R&D Programs• Working Group Assessments:

– Technology, RF Power andEnergy Performance

– Luminosity Performance– Reliability, Availability and

Operability• Summary of R&D that Remains to be

Done and Overall Assessments

Members of the Technology, RF Power andEnergy Performance Working Group

– Adolphsen, Chris - SLAC– Braun, Hans H. -CERN – Chin, YongHo - KEK – Edwards, Helen - FNAL – Hûbner, Kurt - CERN – Lilje, Lutz - DESY – Logatchov, Pavel - BINP – Pasquinelli, Ralph - FNAL– Ross, Marc - SLAC – Shintake, Tsumoru - KEK– Toge, Nobu - KEK – Weise, Hans – DESY– Wilson, Perry - SLAC

Sub-Groups:

• Technology of Injectors, Damping

Rings and Beam Delivery (H. Weise)• Power Sources: Klystrons, Power

Supplies, Modulators and Low Level

RF (Y.H. Chin)• Power Distribution: RF Pulse

Compression, Waveguides, Two-

beam (K. Hübner)• Accelerator Structures (P. Wilson)

Working Group Methodology

Ranking Criteria

• R1: R&D needed for feasibilitydemonstration of the machine.

• R2: R&D needed to finalizedesign choices and ensurereliability of the machine.

• R3: R&D needed beforestarting production of systemsand components.

• R4: R&D desirable for technicalor cost optimization.

• The groups assessed theirrespective systems and topicsfor all machines.

• They examined milestones.• They summarized their positive

reactions as well as theirconcerns.

• The concerns were translatedinto R&D they felt is needed tomitigate them.

• A great effort was then made torank the R&D issues accordingto certain criteria →

LC Designs / RF Technology

• ‘Mature’ Designs– TESLA, based at DESY

• 1.3 GHz Superconducting Technology– NLC, based at SLAC and JLC-X, based at KEK

• 11.4 GHz Normal-Conducting Technology

• ‘Conventional’ Design– JLC-C, based at Super Photon ring-8 GeV (SPring-8) and KEK

• 5.7 GHz Normal-Conducting Technology

• ‘Futuristic’ Design – Aimed for 3 TeV c.m.– CLIC, based at CERN

• Drive Beam Power Source• 30 GHz Normal-Conducting Linac Technology

• NLC/JLC-X: 1 TeV c.m.

– Fill second half of each tunnel with RF components.– Run with same linac beam parameters as 500 GeV operation. Linac

AC power doubles.

– Can increase to 1.3 TeV with lower beam current (lower luminosity).• TESLA: 800 GeV c.m.

– Run at 35 MV/m with 50% higher beam power (linac tunnel lengthremains the same).

– Requires doubling 2 K cooling capacity and number of klystrons andmodulators. Linac AC power increases by 50%.

• CLIC

– Lengthen linac and drive beam.– Drive accelerator requires proportionally higher modulator capacity,

cooling and AC power.

Energy Upgrades

R1 ‘Scorecard’: R&D Needed for a FeasibilityDemonstration of the Machine

Yes

No

No

No

Modulators

YesYesYesCLIC

YesYesNoJLC-C

YesYesNoNLC/JLC-X

No (500 GeV)Yes (800 GeV)

NoNoTESLA

AcceleratorStructures

RFDistributionKlystrons

NLC/JLC-X Structure Development (65 MV/m Unloaded Gradient Goal for 0.5 & 1 TeV Collider)

53 cm Traveling-Wave Structure Making Steady Process Toward an ‘NLC/JLC –

Ready’ Structure

Ø Recently Operated a Structure at 90 MV/m

with an Acceptable Trip Rate (1 per day).

Ø Currently Developing Structures with an

Acceptable Average Iris Radius from a

Wakefield Perspective.

Ø Still Need to Add Slots in Cells for Wakefield

Damping.

Summary of R2 Rankings (R&D Needed to FinalizeDesign Choices and Ensure Reliability of the Machine)

• RF Unit Tests– Assemble system of essential RF Unit components that at minimum

will power a single ‘feed’ of structures:• Modulator• Klystrons and Low Level RF• RF Distribution• Accelerator Structures (at least some with HOM damping).

– Run at nominal power (peak and average) with beam in a machine-like environment.

– Evaluate performance:• Breakdown, quench and failure rates.• Drive beam stability in case of CLIC.

• Technology– Develop fast (< 20 ns) kicker magnet for TESLA Damping Rings.

8 Klystrons, 8 Modulators,4 Three-Cell Coupled-Cavity Pulse Compressors

and 16, 1.8 m C-Band Structures(29 m of Accelerator)

SPring-8 Compact SASE Source

Highlights of the R3 and R4 Rankings

• R3: R&D needed before starting production of systems andcomponents.– Do long-term component testing to qualify lifetimes.– Develop more sophisticated low-level RF systems.

– Verify source laser stability.

• R4: R&D desirable for technical or cost optimization.– Continue fundamental studies of high gradient limitations.

– Develop less expensive, more reliable and more efficient RFcomponents.

– Evaluate feasibility of a helical-undulator based polarized positronsource.

Technology, RF Power and EnergyPerformance Summary

• Found no obvious show stoppers preventing implementation of any ofthe designs with enough resources, effort and time. However,– CLIC appears the furthest away.

– With limited resources, benefit by converging on a common design soon.

• Found no major surprises for energy and technology issues:– Feasibility demonstrations are still required: TESLA (for 800 GeV),

NLC/JLC-X and JLC-C are working to complete these in 2003.

– Major efforts underway to do system tests:

• TTF-2 for TESLA, which is also an FEL facility

• Eight-Pack/NLCTA for NLC/JLC-X

• SPring-8 Linac for JLC-C, which is primarily an FEL facility

• CTF3 for CLIC

• The TRC effort was great learning experience for all involved and thereport will be a valuable resource for selecting a linear collider design.