MR: Space charge and nonlinear field effects

1
MRSpace charge and nonlinear field effects
01 Study of injection process

• Alexandre Molodojentsev
• KEK
• for MR-group

October 4, 2005
2
MR initial beam

• Particle distribution
• Transverse particle distribution has been
  created from the RCS_3GeVparticle distribution
  (v. Noda_050906 95254mp)
• MR_WP Qx 22.4281 / Qy 20.8195
• MR_SCR ?x 12.890 m, ?y 14.160 m
• ?x -1.456, ?y 1.456
• Distribution analysis
• ?x,RMS 7.1901 ? mm.mrad / ?y,RMS 8.3252
  ? mm.mrad
• ?x,99 63.1456 ? mm.mrad / ?y,99
  62.2008 ? mm.mrad
• gt 54 ? mm.mrad H / V 2.025 / 2.198
• gt 81 ? mm.mrad H / V 0.23 / 0.15

3
MR initial beam

• Particle distribution
• Longitudinal particle distribution UNIFORM
  with the parameters
• ?? ? 70 degree, ?p/p ? 0.3

Later replace it by a realistic longitudinal
distribution from RCS.
4
Simulation approach
Main parameters 0.6 MW beam intensity RF ON
(h2) / two harmonics 280kV / 140kV Sextupole
magnets for Chrom.Correction ON NO any
ERRORS.
Tool ORBIT-MPI ( model) 95254 macro
particles Single processor machine (1.6GHz,
1MB???) CPU time 1 turn 75 sec
5
MR initial beam
MR Scraper position particle distribution at
the transverse phase planes
Number of macroparticles 95254
6
MR initial beam
Scraper Aperture 81 ? mm.mrad
MR Scraper position
gt 81 ? mm.mrad H / V 0.23 / 0.15
7
RMS_emittance behavior
8
99_emittance behavior
Scraper Aperture 81 ? mm.mrad
particle losses at MR_SCR
9
Particle losses at the beginning of injection
process
Scraper Aperture 81 ? mm.mrad
10
RMS_emittance behavior
11
99_emittance behavior
12
(No Transcript)
13
(No Transcript)
14
Particle losses at MR_SCR
15
Particle losses at MR_SCR(asymptotic estimation)

Asymptotic 1
Asymptotic 2
16

• Possible sources for the emittance growth

17
Foot_print after 4000 turns
NO sources for skew resonance Only
SpaceCharge and Sextupole resonances.
Qx2Qy64
2Qx 2Qy 3
2Qx-Qy 24
Qx Qy43
4Qy 83
3Qy 62
3Qx 67
18
Normal Sextupole ResonanceQx2Qy64
OFF MOMENTUM (dp/p 0.007) / NO correction
/ VRF 280 kV, h9 Qx 22.34, Qy 20.80 LOST
at SCRAPER (81? mm?mrad) Beam ?x ?y 54
??mm?mrad
COSY symplectic tracking during 5000 turns ( OV
7 3 0 )
Presented on ATAC04
19
Normal Sextupole ResonanceQx2Qy64
Correction of the 1,2 resonance has been
performed by two sextupole correctors CS21 CS31
for the working point close to the resonance Qx
22.40 , Qz 20.80
After correction dp/p0.007
Presented on ATAC04
20
Potential limitation of the beam emittanceby
2Qx-Qy 24 (skew_sextupole)
21
Beam survival scanning of QX 22.2022.50
ATAC2 meeting, March 7, 2003
81 ? mm.mrad
54 ? mm.mrad
COSY (9th order TM)
22
to do

• Particle distribution from RCS including a
  realistic longitudinal distribution and
  including effects of the beam collimator at the
  RCS_MR beam line
• Study of the single particle motion (edge
  particles) for understanding main reasons of the
  emittance dilution
• a lot of things to do