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MR: Space charge different particle distribution & working points

MR: Space charge different particle distribution & working points. Alexander Molodozhentsev for MR-Group. June 21, 2006. Simulation approach…. Q x = 22.42 / Q y = 20.82 … for some reason (not clear yet). Number of macroparticles = 15 10 4. Transverse bin points = 128 128.

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MR: Space charge different particle distribution & working points

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  1. MR: Space chargedifferent particle distribution& working points Alexander Molodozhentsev for MR-Group June 21, 2006

  2. Simulation approach… Qx = 22.42 / Qy = 20.82 … for some reason (not clear yet) Number of macroparticles = 15104 Transverse bin points = 128128 CPU_time/turn ~ 130 sec Single processor Longitudinal bin points = 128 Number of kicks per element = 2 Space Charge - ON Initial: Binomial Transverse distribution Uniform Longitudinal distribution RF - ON Chromatic Sextupoles - ON

  3. What… • (1) • Initial (transverse) particle distribution to provide reasonable / practical • Incoherent tune shift…

  4. Estimation of Incoherent tune shift Bunching-factor Form-factor Form_Factor=1(NO chamber) or 2 (image coefficients) Distribution_Factor=1(Uniform)_1.56…2(Gaussian) … as a function of Bunching_Factor Distribution-factor Beam from RCS: QINC ~ -0.15 Bf ~ 0.33

  5. Initial transverse distributions (#1.3) Footprint without walls Uniform MJoho=1, RMS=100%/2(MJoho+1) Qx0 = 22.42 Qy0 = 20.82 RMS = 54/4 = 13.5 xMAX = (4)1/2RMS

  6. Initial transverse distributions (#2.3) Footprint without walls Binomial - Parabolic MJoho=2, RMS=100%/2(MJoho+1) Qx0 = 22.42 Qy0 = 20.82 RMS = 54/6 = 9 xMAX = (6)1/2RMS

  7. Initial transverse distributions (#3.3) Footprint without walls Binomial - Gaussian MJoho=3, RMS=100%/2(MJoho+1) Qx0 = 22.42 Qy0 = 20.82 RMS = 54/8 = 6.75 xMAX = (8)1/2RMS

  8. X-Y plane: Initial particle distribution MJoho=2 MJoho=1 MJoho=3

  9. RMS and 99% emittance MJoho=2, RMS=100%/2(MJoho+1) Binomial - Parabolic RMS = 54/6 = 9 Qx0 = 22.42 Qy0 = 20.82 xMAX = (6)1/2RMS 600 turns

  10. RMS emittance variation during 10 turns MJoho=2, RMS=100%/2(MJoho+1) Binomial - Parabolic RMS = 54/6 = 9 Qx0 = 22.42 Qy0 = 20.82 xMAX = (6)1/2RMS Initial RMS-Emittance RMS,X = 9.0023 RMS,Y = 9.0017

  11. 99% emittance: Gaussian & Parabolic Qx = 22.42 / Qy = 20.82

  12. Emittance variation Qx = 22.42 / Qy = 20.82 TD: Binomial - Parabolic 1000 turns

  13. What is going on here? What is the source for the emittance growth?

  14. Wp3: Qx=22.42, Qy=20.82 What is going on here? What is the source for the emittance growth? “testHerd” which feels “mainHerd” 300 turns X0 = 5, 10, 15, 20, 25 mm X0/ = Y0 = Y0/ = 0 NO Coupling.

  15. Wp3: Qx=22.42, Qy=20.82 What is going on here? What is the source for the emittance growth? “TAIL” particles “testHerd” which feels “mainHerd” 300 turns X0 = 20, 22, 24, 26, 28 mm X0/ = 0 Y0 = 23, 25, 27, 29, 30 mm Y0/ = 0 Coupling…Sources: CCSX & SpCh

  16. Wp3: Qx=22.42, Qy=20.82 What is going on here? What is the source for the emittance growth? “testHerd” which does NOT feel “mainHerd” Effect of Chromatic Sextupole Field… [4,0] 300 turns X0 = 20, 22, 24, 26, 28 mm X0/ = 0 Y0 = 23, 25, 27, 29, 30 mm Y0/ = 0 Coupling…Sources: CCSX !!!

  17. ATAC’2 meeting, March 7, 2003 Beam survival:scanning of QX: 22.20…22.50 COSY Infinity

  18. ATAC’2 meeting, March 7, 2003 Betatron tune-shift budget

  19. Wp3: Qx=22.42, Qy=20.82 What is going on here? What is the source for the emittance growth? Resonance region for the 54  mm.mrad particles TAIL CORE 4Qx = 90 Structure resonance

  20. What is going on here? What is the source for the emittance growth? “testHerd” which does NOT feel “mainHerd” Effect of Chromatic Sextupole Field… 300 turns X0 = 20, 22, 24, 26, 28 mm X0/ = 0 Y0 = 23, 25, 27, 29, 30 mm Y0/ = 0 Wp3: Qx=22.333, Qy=20.774

  21. What is going on here? What is the source for the emittance growth? “testHerd” which feels “mainHerd” Effect of Sextupole Field & SpaceCharge 300 turns X0 = 20, 22, 24, 26, 28 mm X0/ = 0 Y0 = 23, 25, 27, 29, 30 mm Y0/ = 0 Wp3: Qx=22.333, Qy=20.774

  22. What is going on here? What is the source for the emittance growth? “testHerd” which feels “mainHerd” Effect of Sextupole Field & SpaceCharge Initial conditions for the Test_Particle are NOT changed !!! 300…600 turns X0 = 20, 22, 24, 26, 28 mm X0/ = 0 Y0 = 23, 25, 27, 29, 30 mm Y0/ = 0 Wp3: Qx=22.333, Qy=20.774

  23. What is going on here? What is the source for the emittance growth? “testHerd” which feels “mainHerd” Effect of Sextupole Field & SpaceCharge Initial conditions for the Test_Particle are NOT changed !!! 600…1000 turns X0 = 20, 22, 24, 26, 28 mm X0/ = 0 Y0 = 23, 25, 27, 29, 30 mm Y0/ = 0 Wp3: Qx=22.333, Qy=20.774

  24. RMS_emittance behavior w2: Qx = 22.333 Qy = 20.774 w3: Qx = 22.42 Qy = 20.82

  25. 99% emittance behavior w2: Qx = 22.333 Qy = 20.774 w3: Qx = 22.42 Qy = 20.82

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