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CCDTL with PMQs

REFERENCE beam dynamics: CERN-BE-Note-2009-017 [JB Lallement, A. Lombardi] REFERENCE radioprotection : EDMS 975145 [E. Mauro, M. Silari] REFERENCE PMQ design : ASTER – private communication. CCDTL with PMQs. Design of PMQ Consequences on beam dynamics. CCDTL 50 -100 MeV.

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CCDTL with PMQs

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  1. REFERENCE beam dynamics: CERN-BE-Note-2009-017 [JB Lallement, A. Lombardi] REFERENCE radioprotection : EDMS 975145 [E. Mauro, M. Silari] REFERENCE PMQ design : ASTER – private communication CCDTL with PMQs Design of PMQ Consequences on beam dynamics Alessandra Lombardi BE/ABP

  2. CCDTL 50 -100 MeV • 7 modules with 3 quadrupoles and 9 RF gaps per module DO NOT USE FOR DIAGNOSTICS Alessandra Lombardi BE/ABP

  3. Focusing in LINAC4 Alessandra Lombardi BE/ABP

  4. PMQs for CCDTL Alessandra Lombardi BE/ABP

  5. Consequences • Current • Emittance • Variation of the phase advance for any reason • Can we transport a 50 MeV beam? Alessandra Lombardi BE/ABP

  6. Nominal Beam Dynamics • emittance growth (30-40%) is located before 3 MeV • Bottlenecks : LEBT solenoids, chopper plates and chopped beam dump (wanted) Alessandra Lombardi BE/ABP

  7. Matching currents from 0 to 80 mA • Match to the input of the DTL varying beam current • Find the matched condition to the fixed DTL-CCDTL-PIMS setting • Use the MEBT quadrupoles to match the different beams • End-to-end simulation Alessandra Lombardi BE/ABP

  8. Matching currents from 0 to 80 mA Varying current – conclusions All currents can be matched at the input of the DTL No need to change focusing in the DTL and CCDTL Minor re-matching in the PIMS (first 4 quads) is beneficial Alessandra Lombardi BE/ABP

  9. Transporting a beam with bigger emittance (1.4 times) • Generated a beam with 1.4 times the nominal emittance • CCDTL setting at nominal value • No beam losses and beam envelope ok • PMQs don’t limit the acceptance of the CCDTL. Beam envelopes through the CCDTL . Emittance 1.4 times the nominal , quadrupoles at nominal value. Alessandra Lombardi BE/ABP

  10. Phase advance in CCDTL • Smooth variation of the phase advance • Respect ratio longitudinal /transverse phase advance to avoid resonances. • Following these criteria makes for a current independent matching. • At the moment we don’t see any reason to drastically change the transverse phase advance. • Changes of phase advance per meter – in operation- would be smoother with EMQs. Alessandra Lombardi BE/ABP

  11. 50 MeV beam • Can be transported without changing any of the quads. • The beam size in the first PIMS quad is still manageable • Can be made better by changing the 7 EMQs • Choosing PMQs doesn’t prevent transporting a 50MeV beam. X and y rms beam size vs. length in the CCDTL. RF switched off Alessandra Lombardi BE/ABP

  12. Conclusions-strictly beam dynamics • EMQs allow more flexibility than PMQs [universal statement]. • Having 2/3 PMQs in the CCDTL still allows • Successful acceleration of currents 20-100 mA • Successful acceleration of 1.4 times the nominal emittance • Reasonably ample variation of the phase advance per period to accommodate unforeseen changes in beam • The transport of a 50 MeV beam through the unpowered structure. Alessandra Lombardi BE/ABP

  13. Conclusion-strictly RP • We (beam dynamics) have designed the linac to control the losses to 1 W/m at 6% duty cycle (HP-SPL). • EMQs do not pose any problems up to 6% beam duty cycle (HP-SPL) and losses up to 1 W/m. • A technical solution which allows hands-on-maintenance is still to be found for PMQs at 6% beam duty cycle and 1 W/m losses, due to the presence of Cobalt. Alessandra Lombardi BE/ABP

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