ESS RF Developmentat Uppsala University

Roger Ruber

for the FREIA team

Uppsala University

Roger Ruber - RF Development at UU

ESS-UU Collaboration

• 2009– ESS and UU start discussion on 704 MHz RF development– proposal for ESS dedicated test facility at UU

• 2011– Spring:

• ESS-UU contract on 704 MHz RF R&D• ESS changes to 14 Hz rep rate, 2.89 ms beam pulse

– Fall:• ESS changes pulse modulator strategy• delays UU test stand

• 2012– UU on 352 MHz RF for spoke resonators– keep 704 MHz for future

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Roger Ruber - RF Development at UU 3

RF Development Proposal

1) Contribution to the Technical Design Report (WP8)– design concept 352 MHz spoke source– design concept RF distribution

2) Contribution to the construction planning effort (WP19)– survey test stand infrastructure and requirements– study of upgrade scenarios RF systems for ESS power upgrade

3) Development 352 MHz RF power amplifier for spoke resonators– 1st prototype, test with water load and SRF spoke resonator, incl. LLRF

4) RF system test prototype spoke cryomodule– high power test with 2nd RF power amplifier and LLRF

5) Acceptance testing spoke cryomodules– for all final cryomodules before installation

6) Development klystron pulse modulator– full test incl. klystron and RF system, if available with SRF cavity

ESS TB, 08-Feb-2012

Roger Ruber - RF Development at UU

Timeline for Coming 5 Years

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Objectives

• Validation technical design and acceptance testing of production elements– RF system including power source, amplifiers, distribution and

controls– test with SRF cavity (Lorenz detuning, microphonics, …)

• Increased operation efficiency and decreased cost– minor fault might create a major risk

• contingency in the design– must ensure low beam loss operation

• to prevent activation of accelerator components– major part of the accelerator budget

• must be cost, energy and resource effective for construction & operation

• Training of future staff– participate in prototyping to prepare for operation

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Roger Ruber - Discussion on Studies at Test Stands

Test Stand Matrix

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FREIA: Accelerator & Instrumentation R&D

• New facility at Uppsala University– cryogenic center (LHe and LN2 distribution)

– RF development project for ESS– training of students and staff

• Integrated with physics and astronomy– located at Ångström laboratory– new sub-department (head Tord Ekelöf)– 12 staff (full and part-time)– multiple funding sources

• Hardware– 1000 m2 hall– helium liquefier (>70 l/h)– test cryostat– test bunkers

ESS TB, 08-Feb-2012

FREIA Hall Design

ESS TB, 08-Feb-2012Roger Ruber - RF Development at UU 8

Roger Ruber - RF Development at UU

FREIA Hall Internal Layout

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bunkersRF area cryo

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pres

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Roger Ruber - RF Development at UU

FREIA Cryogenic Infrastructure

• Helium liquefier– 100 l/h with LN2 pre-cooling– 2000 l buffer– distribution box to users

• Interfacing– dewar filling station

• LHe and LN2 dewars

– impure gas recovery from users– 2K pumping station

• General purpose test cryostats– horizontal, like HoBiCat– vertical

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Roger Ruber - RF Development at UU

RF Development Project

• 352 MHz RF Source development– 352 MHz ~350 kW for ESS double spoke resonators

• possible candidate: TH781– requires test at 352 MHz and an output cavity development,– 400 kW pulsed should be ok (500 kW pulsed at 200 MHz),– water cooled

• will study DC or pulsed power supply (energy saving)

– test with water load, – full RF system test with spoke resonator

• Spoke cryomodule testing– build 2nd RF source– full RF system test with complete cryo-module prototype– than cryo-module acceptance testing during construction phase

• Test prototype pulse modulator– with klystron load

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Roger Ruber - RF Development at UU

Proposal for Additional Test Program

• Alternatives RF generation, distribution and controls– test alternatives in relation to staging of beam power and energy– multiple cavities per klystron,

min. overhead on possible vector modulator– multiple klystrons per modulator

• Energy efficiency and recovery– higher efficiency klystrons (long long future)– energy recovery from klystron/load’s cooling water

• Limits in cavity performance– Lorenz detuning– HOM couplers: multipactoring and use as BPMs– multi-cavity field emission

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Roger Ruber - RF Development at UU 13

Conclusions

• Uppsala RF Development redefined to 352 MHz– continued contribution to TDR (in WP8)

• design concept 352 MHz spoke RF power source + RF distribution– new WP19 ”Test Stands”

• survey test stand + study of upgrade scenarios RF systems• prototype 352 MHz source + test prototype spoke cryomodule

– proposal to extend with• testing spoke cryomodules + development klystron modulator

• Uppsala FREIA project– engineering for experiment hall in full swing– negotiations b/w ESS and UU on contract change– UU fully commited

• Uppsala shall … ”taking on such work with priority over work for other possible projects…” (ESS-UU contract agreement)

ESS TB, 08-Feb-2012