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ESS Linac, the world's most powerful proton linac, requires a high-powered RF transmitter for the Spoke Linac. The transmitter must meet specific power, pulse width, and regulation requirements. The project is scheduled for completion by mid-2018.
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ESS Spoke Linac RF transmitter PDR Anders Sunesson, RF group leader
ESS Linac • The ESS linac will be the worlds most powerful proton linac • Beam pulse width is 2.86 ms and pulse rep rate 14 Hz • Protons will be accelerated up to 2 GeV with a beam current of 62.5 mA, beam power 5 MW • Construction in two stages, stage 1 ready 2019 (570 MeV), stage 2 ready 2022 (2 GeV) • ESS has a target to be energy efficient – drives design decisions • Multi-beam IOT project • Cooling water klystrons – high temperature • Regulation overhead optimization
352.21 MHz 704.42 MHz 2.4 m 4.5 m 3.6 m 40 m 54 m 75 m 174 m Target High β Source LEBT RFQ MEBT DTL Spokes Medium β HEBT & Contingency 75 keV 3.6 MeV 90 MeV 220 MeV 570 MeV 2000 MeV RF Requirements
ESS Linac Layout • 155 cavities in total, total length ca 350 m until HEBT High beta RF DTL RF Medium beta RF Low Energy Front end Spoke RF High beta cryomodules Medium beta cryomodules Spoke cryo-modules DTL tanks
RF systems • Power to 155 cavities, one RF station/cavity • High Voltage new development: SML modulator topology • High Power RF Amplifier new development: MB-IOT amplifier (targeted for high beta) • A large part of the RF systems is provided in kind (RF NC linac, Spoke RF stations, LLRF, RF high power distribution, Phase ref distribution) • Not in kind: Medium/High beta Amplifiers (and High Voltage), Master Oscillator • Collaboration Lund Univ Uppsala Univ(FREIA facility)
RF requirementsSpokelinac • The Spokelinac has 26(+) cavitiesorganized in cryomoduleswith 2 cav/CM • The RF frequency is 352.21 MHz • The maximum RF powercoupledto the cavityrequired is ≤350 kW (seepowerprofile in nextslide) • Withexpectedlosses + overhead thisbecomes >400 kW • The flat-toppulsewidthrequired is 2.86 ms, and the pulse repetition rate is 14Hz • Amplitude and phaseof the cavityfieldarerequiredto be regulatedtowithin 0.1% and 0.1° (rms deviation, value tbc) from the set-pointtoavoidexcessive loss (beamphysics) • Has to fit gallery space
Schedule required • The spoke RF sources need to be designed end 2015 • Tender early 2016 • Award contract mid 2016 • Delivery start mid-end 2017, installation starts end 2017 • Install last amplifier Mid 2018 • A challenging schedule