Nominal and no CSR (R56-1 = 55 mm, R56-2 = 59 mm, R56-3 = 0)L1 phase = 21 deg, V3.9 = 55 MV

CSR OFFBC3 OFF

Elegant Tracking

sz1 = 0.275 mm (post BC1 bunch length)

Nominal: (R56-1 = -55 mm, R56-2 = -59 mm, R56-3 = 0)L1 phase = -21 deg, V3.9 = 55 MV

gex 1.0 mm

gex 0.45 mm

CSR ONBC3 OFF

sz1 = 0.275 mm (post BC1 bunch length)

New: (R56-1 = -55 mm, R56-2 = -49.6 mm, R56-3 = 0)L1 phase = -23 deg, V3.9 = 56 MV

gex 0.77 mm

gex 0.42 mm

CSR ONBC3 OFF

sz1 = 0.215 mm (post BC1 bunch length)

New: (R56-1 = -55 mm, R56-2 = -35.2 mm, R56-3 = 0)L1 phase = -25 deg, V3.9 = 59 MV

gex 0.69 mm

gex 0.39 mm

CSR ONBC3 OFF

sz1 = 0.140 mm (post BC1 bunch length)

New: (R56-1 = -55 mm, R56-2 = -17 mm, R56-3 = 0)L1 phase = -26 deg, V3.9 = 65 MV

gex 0.55 mm

gex 0.38 mm

CSR ONBC3 OFF

sz1 = 0.090 mm (post BC1 bunch length)

CSR Emittance Growth vs L1 RF phase (i.e., BC1 compression)

BC3 OFF

Parameter L1 j = -21

L1 j = -23

L1 j = -25

L1 j = -26

Post BC1 sz (mm) 0.275 0.215 0.140 0.090BC1 sE/E (rms) 1.4 1.5 1.6 1.8BC1 R56 (mm) 55 55 55 55BC2 R56 (mm) 59.0 49.6 35.2 17.0V3.9-GHz (MV) 55 56 59 65Final gex (mm) 1.0 0.77 0.69 0.55Final gey

(mm) 0.45 0.42 0.39 0.38

Compression Parameters Over L1 RF Phase Scan(~1-kA constant peak current)

Current Profile is Spiked and Sloped – How to Fix It?

?

No CSR

Use Harmonic Voltage to Slope the Current Profile (2nd order chirp)

L1 phase and voltage adjusted also

Use Harmonic Phase to flatten the Current Profile (3rd order chirp)

L1 phase and voltage, as well as 3.9-GHz voltage all adjusted also

Suggested New 100-pC Configuration

No DeChirper

8-m DeChirper

New

Old

No CSR

Parameter symbol old newPost LH Bunch Length, rms (mm) sz0 1.0 1.0L1 Voltage (MV) V1 223 216L1 RF Phase (deg) j1 -21 -12.2L1 mean Gradient (MV/m) G1 14.1* 13.7*HL Voltage (MV) Vh 55 64.9HL RF Phase (deg) jh -165 -150HL mean Gradient (MV/m) Gh 10.6* 12.5*Post BC1 bunch length, rms (mm) sz1 0.275 0.150BC1 energy spread, rms (%) sE1/E1 1.4 1.6BC1 Energy (MeV) E1 250 250BC1 R56 (mm) R56-1 -55 -55BC2 R56 (mm) R56-2 -59.0 -37.5BC2 Energy (GeV) E2 1.6 1.6BC3 R56 (mm) R56-3 0 0

New 100-pC Configuration (12 A 1 kA)?

* 15/16 cavities powered with 98-MeV injector