1. Ions in ATF
ISG-X
June 20th, 2003

2. Introduction
Fast Beam-ion instability is still a potential limitation in future e- damping rings
Numerous recent observations are consistent with FBII but detailed numerical comparisons have still not been done
With low beam emittance and excellent diagnostics, the ATF provides an opportunity for detailed measurements
Growth rates are calculated to be quite short

3. Growth Rates in Rings

4. Simulations Start from MAD deck At every lattice element:
Track ½ way through
Generate ions
Calculate beam and ion fields on 2-D grid
Calculate kicks on beam and ion macro-particles
Track 2nd ½ of element
Tends to be very slow but …

5. ATF Simulations Use lattice: drlbw44_twiss.tape nx = 15.14 ny = 8.76
1300 elements in ring
gex is too small but gey is too large
 1 mA per bunch with a total of 80 mA
Growth rates scale as N * P  2 x higher pressure = 40 mA

6. ATF Simulations (1)

7. ATF Simulations (2)