C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 Beam Dynamics Justifications of modification of Linac structures C.Limborg-Deprey Parameter goals for the LCLS injector Dipole moment in L01 in L02 Quadrupole moment

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 Gun S1S2 L MV/m L MV/m ‘Laser Heater’ 6 MeV  = 1.6  m  ,un. = 3keV 63 MeV  = 1.08  m  ,un. = 3keV 135 MeV  = 1.07  m  ,un. = 3keV DL1 135 MeV  = 1.07  m  ,un. = 40keV Linac tunnel UV Laser 200  J, = 255 nm, 10ps, r = 1.2 mm Peak Current100 A Charge1 nC  projected,  slice  1.2,1  m.rad Repetition rate120 Hz

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 Nominal tuning – Q = 1nC,10ps  th = 0.72 mm.mrad, r laser = 1.2 mm Solenoid 1  0.3%  gun  2.5  Solenoid 2 20% Linac Field 12 % (E Final = 150 MeV ) E gun  0.5% Balance~ 3% is ok Errrors

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 Combination of errors Using extreme values of parameters deviations meeting regulation specifications Design for 1nC operation even if other operating points are being investigated Using extreme values of parameters deviations meeting regulation specifications Design for 1nC operation even if other operating points are being investigated Param.Nom.UnitsStability Requirement Sol kG  0.02 % Sol20.748kG  1 % Gun Phase  /0-X  0.1  Gun Field 120MV/m  0.5% Charge1nC  5% L01 Field 18MV/m  2.5% 2^6 possibilities = 64 runs  Cannot afford additional emittance growth

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 S-Band linac structure Correction of amplitude term with offset of cell No correction of phase term See J.Schmerge talk and Blue Book P 147, P191

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 L01 entrance coupler Dipole time dependent head-tail kick, integrated over the entrance cell and two first full cell (see Z.Li’s talk) 10ps bunch, Phase = close to crest, 18MV/m  (   )   increase with   = rms of head-tail kick

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 L01 entrance coupler Crest = 0 Max – min for a 10 ps long bunch Rms a 10 ps long bunch a 10 ps long bunch Vrf = 18 MV/m

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 L01 coupler PARMELA simulations of misalignment including transverse wakefield show similar magnitude 200  rad     =  4% increase

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 L01 exit coupler The emittance growth will not exceed 1% at the exit of L01

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 L02 entrance coupler

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 L02 exit coupler

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 Quadrupole moment Quadrupole moment in L01 entrance for 10 ps Dual feed

C.Limborg-Deprey Beam Dynamics Justifying L01 November 3 rd 2004 Conclusion Dual Feed mandatory for both L01 and L02 input couplers output couplers do not absolutely require dual feed Racetrack shape of entrance cell is mandatory for both L01 and L02