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The Front End Test Stand at RAL

The Front End Test Stand at RAL. Ajit Kurup for the FETS Collaboration IAP Winterseminar, Riezlern 4 – 10 th March 2007. Aaron Cheng Simon Jolly Ajit Kurup David Lee Jürgen Pozimski Peter Savage. Mike Clarke-Gayther Adeline Daly Dan Faircloth Alan Letchford Jürgen Pozimski

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The Front End Test Stand at RAL

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  1. The Front End Test Stand at RAL Ajit Kurup for the FETS Collaboration IAP Winterseminar, Riezlern 4 – 10th March 2007

  2. Aaron Cheng Simon Jolly Ajit Kurup David Lee Jürgen Pozimski Peter Savage Mike Clarke-Gayther Adeline Daly Dan Faircloth Alan Letchford Jürgen Pozimski Chris Thomas Christoph Gabor Ciprian Plostinar John Back University of the Basque Country, Spain The FETS Collaboration Ajit Kurup

  3. FETS Layout • FETS main components: • High brightness H- ion source. • Magnetic Low Energy Beam Transport (LEBT). • High current, high duty factor Radio Frequency Quadrupole (RFQ). • Very high speed beam chopper. • Comprehensive diagnostics. Ajit Kurup

  4. H- Ion Beam Extract Electrode Aperture Plate Penning Pole Pieces Discharge Region Anode Ceramic Source Body Copper Spacer Cathode Mica Mounting Flange 10mm Ion Source Development Goals • Increase Pulse Length 200µs to 1.5ms  • Increase Output Current 35mA to 70mA  • Reduce Emittance • Maximise Lifetime 78 mA H- current 500 µs extract pulse 50 Hz repetition rate Ajit Kurup

  5. Laser Diagnostic Non-destructive emittance and profile measurement device Scan the laser across the beam in x and y direction to get transverse profile. Ajit Kurup

  6. Laser Diagnostic Linear travel = 150mm (1m res.) Rotary res. = 0.1mrad Vacuum pumping tank after ion source Amplifiers and power supplies Motion controller Encoders Linear stage Rotary stage Ajit Kurup

  7. Phosphor screen Copper block Fast CCD Camera H- Ion Beam Tungsten screen H- Beamlets Pepperpot Diagnostic • Current Allison-type scanners give high resolution emittance measurements, but at fixed z-position and too far from ion source. • X and Y emittance also uncorrelated, with no idea of X & Y profile. • Correlated, 4-D profile (x, y, x’, y’) required for accurate simulations. • Pepperpot reduces resolution to make correlated 4-D measurement. • Moving stage allows measurement at different z-locations: space charge information. Ajit Kurup

  8. The ion source test facility vacuum tank Mounting flange Pepperpot head Window Support rods Moving rod Camera MK I Pepperpot Setup Ajit Kurup

  9. MK I Results X emittance False colour data image using P43 scintillator Y emittance Ajit Kurup

  10. BOTTOM TOP MK I Problems P43 • Screen too small: only see full beam at small z-postion. • Poor quality holes in tungsten (size, shape, spacing). • Destructive testing of scintillators → • Fast (down to 500ns exposure). • High light output. • Survives beam (<1 micron stopping distance). • Poor mechanical stability. • Mounted at an angle… Al coating profile with quartz and no pepperpot plastic scintillator ruby and Al plate Ajit Kurup

  11. MK II Pepperpot Design • Better support structure. • Cooling for pepperpot head. • Second mount for profile measurements. • Improved DAQ and data analysis. • Fast camera. • Larger screen: 41x41 holes, 120mm x 120mm, 50 micron holes. • Switch to pure and Ce-doped quartz: • Pure survives beam, but slow. • Cerium-doped quartz is fast, high light output, but survival time unknown. Tungsten mesh Pepperpot head Ajit Kurup

  12. RFQ • 60mA H- beam • Accelerate from 65keV to 3MeV. • Input emittance is 0.25 mm mrad • Transmission efficiency is ~95%. • Initial design done by Alan Letchford. • Consider both 4 rod and 4 vane designs and build cold models. • A few pros and cons: Ajit Kurup

  13. Tracking Studies Beam distribution at RFQ input using a waterbag generated beam after tracking from the ion source exit through the 3 solenoid LEBT. ex,rms = 0.33 pmmmradey,rms = 0.33 pmmmrad Input distribution using measurements from the pepperpot after tracking through the 3 solenoid LEBT. ex,rms = 1.21 pmmmradey,rms = 0.93 pmmmrad Presented at LINAC06 Ajit Kurup

  14. Tracking Studies(2) Particle distribution after the RFQ using the generated input distribution. ex,rms = 0.35 pmmmrad ey,rms = 0.35 pmmmrad Transmission ~ 80% (ion source  rfq) Particle distribution after the RFQ using the measured input distribution. ex,rms = 0.62 pmmmrad ey,rms = 0.62 pmmmrad Transmission ~ 40% (ion source  rfq) Presented at LINAC06 Ajit Kurup

  15. 4 Vane Cold Model Simulations Results presented at EPAC06 Ajit Kurup

  16. 4 Vane Simulations - Update 0.4m long Cold Model 1m long section Investigate the effect of the end flanges in simulations and measurement on the cold model CST Studio 2006B Ajit Kurup

  17. 4 Vane Coupling Power In Waveguide to Coax transition Need to find the optimal way to split the power Coupling into the RFQ using coax to loop. Waveguide to iris coupler also being investigated Ajit Kurup

  18. 89mm 27mm 25mm 90mm 66mm First 4 rod simulations Surface current distribution shows the currents are concentrated near the join between the stem and the rod. Results presented at EPAC06 Ajit Kurup

  19. 4 rod simulations CST Studio 2006B Temperature Distribution Thermal Losses Static thermal analysis taking into account only conduction through the copper rods and stems. Background temperature was 25°C and boundaries were open. Surface currents normalised to an average power of 100kW. Ajit Kurup

  20. 4 rod simulations(2) Investigate different geometries near the rod-stem interface with the aim to smoothen out surface current (and hence thermal loss) distribution. Temperature Distribution Surface currents normalised to an average power of 100kW. Thermal Losses Ajit Kurup

  21. Bead Pull Diagnostic ISIS 4 rod RFQ Cold Model Ajit Kurup

  22. Cold Model Manufacturing New major-minor vane design and improved undercut design Old vane design Machining at IC Ajit Kurup

  23. 3.2 m ‘CCL’ type re-buncher cavities Chopper 1 (fast transition) Chopper 2 (slower transition) Beam Chopper and MEBT Scheme C Ajit Kurup

  24. DTL RFQ Fast Chopper Slow Chopper Re-bunching cavities Re-bunching cavities Quadrupoles Beam Dumps Beam Chopper and MEBT Scheme A MEBT Schemes Ajit Kurup

  25. Summary and Plans • Ion Source • Improve emittance and lifetime • LEBT • 3 solenoid MAFIA simulations done. Engineering of the solenoids is next. • RFQ • 4 Vane • Investigate ways to shift dipole modes. • Input power coupling. • 4 Rod • Investigate cooling solutions. • Chopper and MEBT • FPG nearly met spec. SPG development beginning. • Cavity and quadrupole design in progress. • Diagnostics • Manufacturing of MKII Pepperpot in progress. • Laser profile first measurements end of year. • Laser emittance first design phase. Ajit Kurup

  26. Timescale R&D phase Design & Construction phase Installation and Commissioning phase Ajit Kurup

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