LCLS-II Bypass Line Design Goals P. Emma, July 7, 2010. Provide 14-GeV (?) electron bypass line from sector-20 around LCLS-I , feeding new undulators south of LCLS-I at 2 to 4-deg angle Use existing PEP-II 9-GeV line on linac ceiling (2’ above & 2’ south of linac) - PowerPoint PPT Presentation
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LCLS-II Bypass Line Design Goals P. Emma, July 7, 2010 Provide 14-GeV (?) electron bypass line from sector-20 around LCLS-I, feeding new undulators south of LCLS-I at 2 to 4-deg angle Use existing PEP-II 9-GeV line on linac ceiling (2’ above & 2’ south of linac) Sneak line around crowded BSY and BTHW Bore new hole in 17-m thick iron m-plug wall Preserve 0.6-mm emittance with up to 3 kA at 14 GeV Include diagnostics and corrections in design
Transcript
LCLS-II Bypass Line Design GoalsP. Emma, July 7, 2010
Provide 14-GeV (?) electron bypass line from sector-20 around LCLS-I, feeding new undulators south of LCLS-I at 2 to 4-deg angleUse existing PEP-II 9-GeV line on linac ceiling (2’ above & 2’ south of linac)Sneak line around crowded BSY and BTHWBore new hole in 17-m thick iron m-plug wallPreserve 0.6-mm emittance with up to 3 kA at 14 GeVInclude diagnostics and corrections in design
Bypass-Line ComponentsExtract beam out at 20-5 (use half of sec-20 RF)Rolled x/y bends to existing 9-GeV PEP-II line(Existing PEP-II extraction bends blow up LCLS emittance by factor of 4 – redesigned here)Use 1-km of existing FODO cells (bmax = 400 m)
Also use long FODO as emittance diagnosticRemove 4.6-mrad pitch of linac (as in LCLS-I)Bend south with LCLS bend-cells (four 1-deg cells)Keep beamline at bypass line height (25.5” up)Bore new tunnel in hill 25.5” higher than LCLS-IAdd final wire scanner section & undulator matching (+ room for ECHO seeding)
47”
66”
Inside Linac Vault - Looking Down-Beam
120”
132”
LINAC
25.512”
25.512”
9-GeV17” 3-GeV
(ID-344-013-30)
LCLS-II Bypass Layout
Dx = 25.5”
PLAN VIEW
ELEVATION VIEW
N
Sector 20-517-m thick m-plug wall
17-m thick m-plug wall
Dy = 25.5”
Sector-20(20-5)
m-plug wall
2324 26 28 30
25 27 29existing quads on ceiling
m-plug walleight 0.5-deg bends
LCLS-I Head-House Layout(R. M. Boyce)
South-Side Head-House Port
~5 m
Linac Tunnel Approaching BSY
Bypass Line will pass through
most congested area in BSY
Bypass Line will pass through
most congested area in BSY
LINAC
SIT Lineto PEP-II
Quadrupole magnet here?
problem area
Twiss functions in Elegant
With CSR (uniform temporal dist.) – note that ISR is no problem
gex,y = 0.6 mm
Longitudinal phase space at 13.6 GeV, 3 kA, with CSR(uniform temporal dist.)
Energy spread (green) & bunch length (red) vs. z
QuestionsIs this 2-4-deg option the choice (2 other options exist, but all need a bypass line)?Will we run at 7 GeV/360 Hz, or 14 GeV/120 Hz, or both (assuming both for now)?Can a new hole be bored in the 17-m thick m-plug wall ?Can we tunnel the new undulator hall 25.5” higher in elevation than LCLS-I ?Do we need a jumper line from LCLS-I to LCLS-II, and the reverse?Do we want a horizontal spreader to someday feed 2 undulators in the new hall ?
