Recent works

• Tolerance budget study on two stage compression– A code has been developed for automatically find

the working point of the two stage compression base on litrack

– Multi-objective genetic algorithm (moga) code is used to get the smallest jitter of the energy, peak current and the arriving time

The jitters of the linac parameterstols.err = [ 0.05 % inj_arr ps 2 % inj_dQ % 0.05 % L1_pha deg 0.02 % L1_volt % 0.05 % Lx_pha deg 0.02 % Lx_volt % 0.05 % L2_pha deg 0.02 % L2_volt % 0.05 % L3_pha deg 0.02 % L3_volt % 0.001 % BC1_dR56 0.001 % BC2_dR56 ];

The variables and goals• Variables

– R56 of 1st compressor: -0.04~-0.06m

– R56 of 2nd compressor: -0.01~-0.03m

– Compression ratio of the first compressor: 8~20

• Goals (jitter)– Energy: 0.02%– Peak current: 10%– Arriving time: 20fs

1st generation of the moga: variables

1st generation of the moga: goals

Jitters have same effect on the arriving time and peak current

In the energy case, it is seems different.

28th generation of the moga: variables

1st R56 is towards -0.06m, while 2nd R56 is around -0.01~-0.014m

1st stage compressing ratio is around 13~152nd R56 is correlated

with 1st stage compressing ratio

28th generation of the moga: goals

Bad case

dE(0.02%)

dI(10%) dt(20fs)

inj_arr 0.22294 0.259383 0.087965

inj_dQ 0.338978 0.598442 0.201874

L1_pha 0.30541 0.621765 0.700465

L1_volt 0.253763 0.142405 0.468724

Lx_pha 0.050167 0.526496 0.01209

Lx_volt 0.04418 0.014999 0.083152

L2_pha 0.313746 0.077781 0.141824

L2_volt 0.311427 0.010803 0.143098

L3_pha 0.118905 1.58E-05 1.58E-05

L3_volt 0.134476 6.33E-06 6.33E-06

BC1_dR56 0.020209 0.010617 0.026692

BC2_dR56 0.005807 0.000612 -0.00931

total 0.744873 1.056402 0.898496

• With the giving jitter of the linac parameters, it seems that the optimized 1st R56 moves toward -0.06m, the 2nd R56 is around -0.01~-0.014m, and the compression ratio is around 13~16.

• The 1st s-band linac section has the tightest requirements on phase jitter, and similar in the case of phase of the x-band linearizer.

1D tracking of good sample

Injector exit Linac exit

Summary and plans

• We have established an effective procedure of jitter optimization with every factor in 1D tracking.

• The first result showed the tight jitter budget of the x-band linac even with optimization.

• Wake from the real x-band structure should be used instead of the default x-band wake in litrack. The voltage and the length of the structure should be checked.

• More work should be done on the jitter budget assignment among the 3 linac sections.

• Large R56 of the 1st stage should be carefully studied with the lattice design and 6D tracking.