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THE RING AND TRANSFER LINES

THE RING AND TRANSFER LINES. PULSED NEUTRON. CHOSE WAVE LENGTH OF INCOMING NEUTRONS USING TIME CHOPPER. ISSUES. VERY HIGH PROTON POWER UNPRECEDENTED NUMBER OF PROTON ACCUMULATION 2 X 10 14 SPACE CHARGE LOSS AND COLLIMATION INSTABILITIES AND IMPEDANCE HANDS ON MAINTENANCE

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THE RING AND TRANSFER LINES

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  1. THE RING AND TRANSFER LINES

  2. PULSED NEUTRON • CHOSE WAVE LENGTH OF INCOMING NEUTRONS USING TIME CHOPPER

  3. ISSUES • VERY HIGH PROTON POWER • UNPRECEDENTED NUMBER OF PROTON ACCUMULATION 2 X 1014 • SPACE CHARGE • LOSS AND COLLIMATION • INSTABILITIES AND IMPEDANCE • HANDS ON MAINTENANCE • LIMIT LOSS TO < 1 WATT / m (10-4 LOSS) • STRICT PROTON DISTRIBUTION REQUIREMENTS AT THE TARGET • INJECTION PAINTING • RELIABILITY, AVAILABILITY AND MAINTAINABILITY

  4. RING ARC FUNCTIONS • Perfect matching: FODO arc doublet straight • Arc achromats • Zero dispersion in straights • Chromatic correction with arc sextupoles • Resonance correction with straight correctors • Minimum change

  5. RING STRAIGHT FUNCTIONS • Separate functions in each straight • Four straights: 12.5 m; 2 x 6.85 m • Injection modules • Two-stage collimation • 3 (h=1)+1 (h=2) interchangeable RF cavities • Beam-in-gap kicker • Empty section for future use

  6. RING LATTICE FUNCTIONS

  7. INJECTION LOSSES and STRIPPING FOIL • EXCITED STATE HO EMERGING FROM FOIL • 2 ~ 10 % DEPENDING ON FOIL THICKNESS • SINGLE AND MULTIPLE SCATTERING • NUCLEAR SCATTERING • DEPENDS ON FOIL THICKNESS AND SIZE (EFFECTIVE LINAC EMITTANCE) • LINAC BEAM MISSING THE FOIL • STABILITY OF LINAC BEAM • CONTROLLED DUMPING TO INJECTION DUMP • ISSUE OF TWO STRIPPED ELECTRON DUMPING (~2 KW) • COLLECTION OF TWO STRIPPED ELECTRONS • FOIL HEATING AND LIFE

  8. Injection layout Fixed chicane Dynamic bump Dynamic bump

  9. PHASE SPACE PAINTING • CREATE DESIRED PHASE SPACE DISTRIBUTION FROM LINAC BEAM • TO CONTROL LOSS DUE TO SPACE CHARGE • REDUCE FOIL HITS BY CIRCULATING BEAM • TO SATISFY DISTRIBUTION AT THE TARGET

  10. LINAC TO RING INTERFACE PARAMETER Trans. Emitt. < 0.5 pi mm mr (norm, rms) Energy spread ±0.3 MeV (rms) Bunch spread ±1.5 deg (rms) Energy centroid error ± 1.5 MeV max Phase centroid error ± 2 degrees Beam halo outside 5 sigma <10-4 Beam chopper gap < 10-4

  11. y y foil foil x x BASIC PAINTING SCHEMES Correlated painting Anti-correlated painting

  12. CORRELATED PAINTING Correlated painting with/without space charge

  13. ANTI-CORRELATED PAINTING Anti-correlated painting with/without space charge

  14. PROTON DISTRIBUTION AT TARGET I • LESS LOSS IN RING • UNSATISFACTORY TARGET DISTRIBUTION

  15. PROTON DISTRIBUTION AT TARGET II • HIGHER LOSS IN RING • GOOD DISTRIBUTION AT TARGET

  16. LONGITUDINAL PHASE SPACE PAINTING • KEEP EXTRACTION GAP CLEAN • MEBT CHOPPER • REDUCE SPACE CHARGE EFFECT • TO HAVE HANDLE ON LONGITUDINAL AND TRANSVERSE INSTABILITIES • USE ENERGY SPREADER TO CONTROL THE ENERGY SPREAD WITHOUT ENERGY TAIL • INJECTING IN DISPERSION FREE STRAIGHT GIVES FREEDOM TO CHOOSE ENERGY SPREAD

  17. LONGTUDINAL DISTRIBUTION ESS • ESS LONGITUDINAL DISTRIBUTION AFTER 1000 TURN INJECTION

  18. INJECTION WITH LINAC PHASE RAMPING • ENERGY VARYING INJECTION LEAVES LUMPINESS IN LONGITUDINAL DISTRIBUTION

  19. LONGITUDINAL DISTRIBUTION WITH GOOD ENERGY DISTRIBUTION FROM LINAC • ENERGY SPREADER CAVITY 3.5 MV • Df =100KHz

  20. INSTABILITIES • LONGITUDINAL • TRANSVERSE

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