Wi =Length_element/ Length_section Wi=0 if ion is unstable. Both growth rate and tune-shift are small if there is a. Smaller (vertical) beta function Long bunch spacing. Peak growth rate of FII for CO+. Pwiggler= 2.0nTorr ; Plong_straight = 0.1nTorr P_arc= 0.5nTorr.
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Wi=0 if ion is unstable
Both growth rate and tune-shift are small if there is a
Growth time is less than 1 turn!
Peak growth rate of FII for H+
The growth time is 100 times longer than CO+!! (H+ has small cross section and it is likely unstable after several damping time)
17km ring has a longer growth time
Shorter average growth time
The Tune shift caused by CO+ is 30~100 times larger than H+!!
H+ is dominant component!
Larger tune shift
Nbunch=20, P=10nTorr, 20% is CO+
Radiation damping time 30ms
Close to the experiment
Tune shift is very small
Calculation (don’t know the optics)
0.9 ms for 100% CO+
5ms for 100% H+
There is no FII observed in usual operation of B-factories except at the beginning of the operation after long shutdown (suppressed by Feedback?)
ILC has a faster FII than B-factories
Stable Zone with gap (linear model)
Trapping time(0.1MHz for 6km ring)
The decay time of ion-cloud is about 1 times of the ion oscillation period:
Wiggler section need a short gap
Light ion need a short gap.
Gap in KEKB HER: 69.38m(230ns)
Gap in PEPII HER: 40m(130ns)
Damping ring is different from B-factories & Light source
The required gap varies with time!
Gap=8 bunch spacing=49.2ns
Trapping location varies with time
Peak growth rate of FII and tune shift with CO+