Presentation on theme: "Upgrades to the ISIS Facility ISIS Accelerator Division John Thomason."— Presentation transcript:
Upgrades to the ISIS Facility ISIS Accelerator Division John Thomason
ISIS Accelerators H ion source (17 kV) 665 kV H RFQ 70 MeV H linac 800 MeV proton synchrotron Extracted proton beam lines The accelerator produces a pulsed beam of 800 MeV (84% speed of light) protons at 50 Hz, average beam current is 230 A (2.9× ppp) therefore 184 kW on target (148 kW to TS-1 at 40 pps, 36 kW to TS-2 at 10 pps).
ISIS Upgrades Present operations for two target stations Operational Intensities: 220 – 230 μA (185 kW) Experimental Intensities of 3 ppp (equiv. 240 μA) DHRF operating well: High Intensity & Low Loss Now looking at overall high intensity optimisation Study ISIS upgrade scenarios 4) Upgrade 3) + long pulse mode option 0) Linac and TS1 refurbishment 1) Linac upgrade leading to ~0.5 MW operations on TS1 2) ~3.3 GeV booster synchrotron: MW Target 3) 800 MeV direct injections to booster synchrotron: 2 – 5 MW Target
2) Based on a ≈ 3.3 GeV RCS fed by bucket-to-bucket transfer from ISIS 800 MeV synchrotron (1MW, perhaps more) 3) RCS design also accommodates multi-turn charge exchange injection to facilitate a further upgrade path where the RCS is fed directly from an 800 MeV linac (2 – 5 MW) 1) Replace ISIS linac with a new ≈ 180 MeV linac (≈ 0.5MW) ISIS MW Upgrade Scenarios
Power / Benefit / Cost £ + Risk Neutrons Power TS2 Existing TS1 Upgraded TS1
ISIS Upgrades, Developments and R&D Work We have on-going research and studies to develop and fully exploit the machine map out the best development routes define principle upgrades undertake basic R&D into physics of high intensity beams Main focus presently ~180 MeV Injector Upgrade summarised in the following pages holistic optimisation including targets, neutronics, … “at the user” Next steps Exploring the possibilities for optimistic & less optimistic funding scenarios Mapping out the best options for a 1-2 MW short pulse neutron source Development and research on present machine
ISIS Injection Upgrade A New 180 MeV Injector Update old linac Increase beam power ~0.5 MW Advantages Reduces Space Charge (factor 2.6) Chopped, Optimised Injection & Trapping Challenges Injection straight Activation (180 MeV) Space charge, beam stability,.... New 180 MeV Linac 70 MeV Linac 800 MeV Synchrotron TS1 TS2 MICE
Snapshots of the work: challenges of getting 0.5 MW in the ISIS Ring Longitudinal Dynamics Transverse & Full Cycle 3D Dynamics Injection Other Essentials: Activation, Diagnostics Analytical WorkSimulation Results Test Distribution RF BucketVariation of key parameters Evolution of bunch Accelerated distributions in (x,x’),(y,y’),( ,dE) Predicted Space Charge Limit Coherent Tune Shift and Resonance Single particle tune shift distributions at 0.5 MW Injected distributions in (x,x’),(y,y’),( ,dE) Foil temperatures Injection Straight Injection Straight Modelling Activation vs EnergyActivation Measurements Electron Cloud MonitorStrip-line Monitor/Kicker ISIS Injection Upgrade Ring Physics Study
Possible ≈ 3.3 GeV RCS Rings
Energy0.8 – 3.2 GeV Rep Rate50 Hz C, R/R m, 9/4 Gamma-T7.2 h9 f rf sweep MHz Peak V rf ≈ 750 kV Peak K sc ≈ 0.1 ε l per bunch≈ 1.5 eV s B[t]B[t]sinusoidal 5SP RCS Ring
800 MeV, Hˉ Linac Design Parameters Grahame Rees, Ciprian Plostinar ( ) Ion SpeciesH-H- Output Energy800 MeV Accelerating StructuresDTL/SC Elliptical Cavities Frequency324/648 MHz Beam Current43 mA Repetition Rate30 Hz (Upgradeable to 50 ) Pulse Length0.75 ms Duty Cycle2.25 % Average Beam Power0.5 MW Total Linac Length243 m
Capacity upgrade scenarios “Traditional” 3-stage MW upgrade scenario could be extended so 3.2 GeV RCS includes multiple extraction straights (or switchyard in EPB), with or without 800 MeV linac. Stacked rings (as at CERN PSB) could be implemented as part of AC magnet replacement programme. Would require increased linac performance, but otherwise it is an engineering challenge to minimise off time during installation rather than an accelerator physics challenge, and would be a very predictable upgrade.
One synchrotron with several extraction straights? Flexible Easy extraction of proton beams of different energies, intensities and repetition rates to suit wide range of neutron experiments Linac Synchrotron Target station #1Target station #2 Target station #4Target station #3 “Efficient” footprint Maximises total number of neutron beam lines Would need to drive trim quads. and steerers differently for different energies and intensities, but trim quads. and steerers are pulsed anyway, and so changing trim magnet current profiles from acceleration cycle to acceleration cycle should raise no fundamental complications.
Head-tail instability Key for high intensity proton rings New simulation code: Set 3Di Model losses, benchmark on ISIS Ring High Intensity Beam Studies on ISIS Half-integer intensity limit in proton rings Using the ISIS ring to study halo formation (Y,Y) Higher order loss effects and images Investigating complex loss mechanisms Image driven resonance Loss vs Q measurement Vertical dipole motion along bunch on successive turns Simulation Measurement Y profile Some of our R&D Studies Y profile Turn Samples along bunch Vertical difference signal (along bunch, many turns)
High power front end (FETS) RF Systems Stripping Foils Diagnostics Targets Kickers etc. To realise ISIS upgrades and generic high power proton driver development, common hardware R&D will be necessary in key areas: In the neutron factory context SNS and J-PARC are currently dealing with many of these issues during facility commissioning and we have a watching brief for all of these Active programmes in some specific areas Necessary Hardware R&D