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The RAL Front End Test Stand David Findlay ISIS Accelerator Division Rutherford Appleton Laboratory Oxfordshire, UK. STVLTVS EST QVI ACCELERATORIBVS CVRANDIS VICTVM QVAERIT. CCLRC Council for the Central Laboratory of the Research Councils Member of RCUK (Research Councils UK)
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The RAL Front End Test Stand David FindlayISIS Accelerator DivisionRutherford Appleton LaboratoryOxfordshire, UK STVLTVS EST QVI ACCELERATORIBVS CVRANDIS VICTVM QVAERIT
CCLRC • Council for the Central Laboratory of theResearch Councils • Member of RCUK (Research Councils UK) • BBSRC, CCLRC, EPSRC, ESRC, MRC, NERC, PPARC • Provides large facilities for UK science • Lasers, neutrons, synchrotron radiation • BBSRC Biotechnology & Biological Sciences Research Council • CCLRC Council for the Central Laboratory of the Research Councils • EPSRC Engineering & Physical Sciences Research Council • ESRC Economic & Social Research Council • MRC Medical Research Council • NERC Natural Environment Research Council • PPARC Particle Physics & Astronomy Research Council
CCLRC Daresbury Laboratory SRS 4GLS Rutherford Appleton Laboratory ISIS Diamond
ISIS • ~270 people total • Accelerator Division (~95) • Diffraction & Muons Division • Instrumentation Division • Spectroscopy & Support Division • Target Division • David Findlay Photonuclear physics / light nuclei • Photofission • Radioactive waste • Accelerator services • Gemstones (in private sector) • Medical sterilisation (in private sector) • ISIS
Why a [proton driver] front end test stand? • Prove key elements of high power proton accelerators • Applications of a RAL test stand Generic Spallation neutron sources Neutrino factories Transmutation machines Tritium generators Energy amplifiers Training / Young people / Real hardware Specific ISIS upgrades UKNF UK academic accelerator community
ISIS • World’s leading spallation neutron source • Natural wish to stay at or near front • Upgrade strategies / CCLRC funding / ASTeC • (ASTeC = CCLRC’s Accelerator Science & Technology Centre) • UK Neutrino Factory • Strong drive from UKNF community • PPARC support for proton driver R&D • Synergies with possible ISIS upgrades • UK academic community • Imperial College - CCLRC joint appointment • Lecturer / Senior Lecturer in Accelerator Science • Extend university accelerator centres to protons
What’s in a front end? • Ion source, LEBT, RFQ and beam chopper • Why does it matter? • Where beam quality set for entire machine • What has to be tested? • New, high performance ion sources, RFQs,beam choppers • ISIS 0.16/0.24 MW Now • PSI 0.75 MW [not pulsed]SNS 1 MW Near future • JPARC 1 MW Near future • NF 4 MW — a big step! Further away • [ISIS 1, 2, 5 MW Plans]
So, planning to build front end test stand at RAL But already had one!
ISIS RFQ Test Stand • RFQ to replace ISIS Cockcroft-Walton • 202.5 MHz, 4-rod, 35 keV i/p, 665 keV o/p50 mA / 10% DF design, 30 mA / 2% DF use • Test stand built to characterise and soak test • Met specifications • Soak tested successfully for >2000 hours
Proton driver front end test stand at RAL • ISIS Accelerator Division CCLRC/ASTeC • Imperial College PPARC • Warwick University PPARC • + ? • + 1½×½ SY/year EU (HPRI-CT-2001-50021) • + 5 ×½ SY/year EU (HIPPI/CARE/ESGARD) • Mike Clarke-Gayther, Dan Faircloth, Frank Gerigk, Paul Harrison, Alan Letchford, Ken Long, ...
Relationship with CERN test stand • Formal cooperation through HIPPI • Two approaches to beam chopper • But different • CERN test stand for Linac4 then SPL • Proton / H– ion sources • RAL test stand more generic • Differences reflect organisation’s missions
75 keV 2½ – 3 MeV H– ion source 60 mA2 ms RFQ234 MHz Bunch + accel-erate Chopper Switch in 2 ns for~0.1 ms LEBT Match ion source to RFQ Beam stop Diagnostics Transverse emittances,energy & energy spectra,bunch widths, halo, ... Block diagram of RAL front end test stand
H– ion source — Development to ~60 mA requiredBased on ISIS H– ion source (35 mA) LEBT — Revision of ISIS RFQ LEBT probably sufficient RFQ — Base on ISIS & ESS 4-rod RFQsISIS RFQ designed for 10% RF duty factor cf. ISIS 2%75 keV in, 2½–3 MeV out, 234.8 MHzMost expensive item: ~1–2 MW RF driver Beam chopper — Development requiredBased on ESS concept But need ion source, LEBT and RFQ to test beam chopper
H– ion source R&D programme — for future high power proton accelerators (e.g. for future spallation neutron sources) — × ~10 output required Important milestone passed Successful thermal modelling of world leading ISIS ion source — extraction of surface temperatures Excellent agreement between calculated and measured thermocouple temperatures Anode 600°C Cathode 200°C Ab initio calc. Meas. °C °C Anode t/c 456 400 – 600 Cathode t/c 501 440 - 530 Body t/c 416 390 - 460 1 inch
1145 mm Beam Fast switch Slow switch Buncher cavity Buncher cavity Close-coupled chopper module
Beam chopper R&D programme — specialised hardware — fast, high voltage pulser specified and procured 1½ kV rise in <2 ns
RAL front end test stand for: • ISIS upgrade • Front end of 180 MeV linac • 234.8 MHz DTL to ~80 MeV704.4 MHz SCL to 180 MeV (like Linac4 at CERN) • UK neutrino factory • High power proton accelerators in general
New ~180 MeV linac Present 70 MeV linac ISIS half-megawatt upgrade
UK Neutrino Factory New ~180 MeV linac
With existing funding, at end of three years, i.e. by March 2007, expect to have • Dedicated area (in R8 (probably)) • Lead shed (shield against RFQ X-rays) • Support structure / Stands • Operational ~60 mA H– ion source available • LEBT assembled • Design for RFQ • Specification for RF driver • Proven electrical design for beam chopper • Design for quadrupoles and cavities for chopper • Specification of diagnostics
6 7 27½ 12 5 m 12 1½ 4½ 7 7 5½ 10 Mag. spectr. Ion source LEBT RFQ Chopper Diagnostics RF driver area R8, area easily available 290 m² More space available
Opportunities to take advantage of: • Area in R8 already well provided — space, electricity, water, air, crane, loading bay, on main ISIS controls circuit, … • Significant existing hardware — high power arc driver and high power extraction pulser for H– ion source, TMPs, gas scattering spectrometer, magnetic spectrometer, emittance scanners, data acquisition systems, 200 kW RF driver, ...
2004–2007 Overall scheme, design, infrastructure, specifications, some hardware 2007 Complete scheme Hope to demonstrate high quality chopping of ~60 mA H– beams at ~2½ MeV [End]
RAL beam chopper design • Robust design with explicit provision for high power beam collection Slow transmission line 0 1 0 1 Up to 100 µs Lumped line — thermally hardened 2 ns 8 ns