LCLS Conceptual Design Report - Stanford Synchrotron Radiation ...

Table 6.5 PARMELA Output Parameters.
L C L S C O N C E P T U A L D E S I G N R E P O R T
Parameter Value
Bunch charge 1.0 nC
Booster phase 2°
Bunch length 2.9 ps rms
Energy 150 MeV
Integrated energy spread, σ γ γ 0 0.10% rms
slice
Slice energy spread, σγ γ 0 0.005% rms
Emittance at 20 cm from exit of L0-2 for 0.7 ps rise time;
below e th in µm/no. particles tracked:
εn,rms (µm); below for
140/120 MV/m:
0.3/10 K 0.926/0.929
0.5/10 K 0.952/0.956
0.3/100 K 0.922/
0.3/200 K /0.919
0.5/100 K 0.948/
0.5/200 K /0.958
Emittance at 20 cm from exit of L0-2 for 0.35 ps rise time;
below eth in µm/no. particles tracked:
0.3/20 K 0.80/
0.3/100 K 0.78/ 0.80
6.6.3 Optimization for 120 MV/m
ε n,rms (µm); below for
140MV/m / 120MV/m:
Typically S-band rf guns operate with peak rf fields of 120 MV/m or lower. Higher fields
usually lead to excessive dark current or frequent rf breakdowns. Although a great deal of care
will be taken to construct the LCLS gun so as to avoid these problems (the load-lock should help
as well), the initial gun operation is anticipated to be at about 120 MV/m. In this section, a
reoptimization of the injector parameters is made for the case of 120 MV/m in order to determine
more exactly the emittance achievable during initial operation.
6-59 ♦ I NJECTOR