1. Bunch Separation with RF Deflectors
D. Rubin,R.Helms
Cornell University

2. In the event that an injection/extraction kicker
with pulse width of 6ns is not practical,
then we can increase effective bunch spacing with RF separation
injection
extraction
Transverse RF
kicker

3. ILC Damping Rings Workshop
extraction
kicker
Transverse RF
kicker
injection
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

4. ILC Damping Rings Workshop
Separation with transverse RF
Timing
t = nTRF (t = bunch spacing)
N = Trev/TRF
t = (m+1/2)TTR (opposite kick for consecutive bunches)
Trev/TTR = (M+1/2) (opposite kick for the same bunch on consecutive turns)
TTR= [n/(m+1/2)] TRF
n=2, m=1 => TTR=(4/3)TRF
fRF=650MHz
fTR=487.5MHz
N=14402
M=10801
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

5. ILC Damping Rings Workshop
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

6. ILC Damping Rings Workshop
More Timing
Train spacing corresponds to bunch spacing in linac (337ns)
- Extract damped bunches from the tail of each train
(For extraction there are 2t ~6ns for kicker rise time and > 49ns fall time
- Inject undamped bunch at head of train
(For injected bunch there are > 49ns for kicker rise time and 2t fall time.
Bunches near the head of the train are more tolerant of kicker tail)
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

7. ILC Damping Rings Workshop
Transverse Kick
A = 9e-6 m-rad
=>Beam size (=25m) = 15mm
In order to clear septum > 15mm 
Suppose each cavity kick =  0.3mrad
Then 3 cavities =>  0.9mrad =>  = 22.5mm
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

8. ILC Damping Rings Workshop
Deflecting RF
KEK B crab cavity (Akai 24-dec-2003)
Achieve >21MV/m peak surface field in full scale test
=> 1.4MV transverse/cell
Suitable for 2A LER beam
(23kW HOM power)
Installed in HER and LER January 2007
Testing began a few weeks ago!
(1.4MV -> 1.5MV for super B-factory)
At 5GeV beam energy  = 0.3mrad/cell
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

9. ILC Damping Rings Workshop
KEK-B Crab Cavity
K.Oide (19 Jan 2006)
500MHz
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

10. ILC Damping Rings Workshop
K.Oide (19 Jan 2006)
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

11. ILC Damping Rings Workshop
Q vs E
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

12. ILC Damping Rings Workshop
Beam tests began February 2007
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

13. ILC Damping Rings Workshop
Summary
4-6 Superconducting RF kickers double bunch spacing
Beam tests of crab cavity started in February 2007
Bypass lines must have identical path lengths
RF stability for closing the bump
TR >> L -> uniform kick over length of bunch
Dynamic aperture?
Full wave bypass for symmetry?
Next step:
Implement crabbing RF and separation transfer line in base line lattice and test stability and dynamic aperture with tracking simulation
David Rubin
Cornell University
ILC Damping Rings Workshop
5-March-2007

14. DR INJECTION/EXTRACTION SCHEMES
F. Marcellini,D.Alesini,S.Guiducci,P.Raimondi
The length of the DR is properly chosen so that, after one turn, the bunches are 2pi /F (F is the compression factor) out of phase with respect to the RF voltage of the 2nd RF deflector. The residual transverse kick is completely compensated by the 1st RF deflector because the betatron phase advance between the two devices is 180 °. In this way the bunches are progressively recombined.
By using the combination of 2 or more frequencies it is possible to increase the ratio /MAX.This means that the needed maximum deflection can be reduced or that the compression factor can be increased.
Even if TW RF deflectors are fast devices, a gap in the DR filling pattern has to be introduced to take into account their finite filling time. Minimizing this filling time is important to have the shorter gap possible.
If the filling time (F) of the deflectors is less than TDR it is possible to inject or extract the bunches without any gap in the DR filling pattern.
 should be  * depending on the ring optics and septum position. Considering a single RF frequency 
 /MAX=1-cos(2/F)

15. EXAMPLE OF A TW RF DEFLECTOR DESIGN
F. Marcellini, (see TESLA Report )
Single cell dimensions for 2 possible operating mode considered
p/2
p/3
a [mm]
41.8
b [mm]
133
133.5
D [mm]
58.06
38.70
Deflector characterization by simulations
mode
p/2 (f≈1.3GHz)
HFSS
MAFIA
Series
impedance
0.578
0.552
Quality factor
17000
17300
Shunt
16.07
15.95
Attenuation
0.0180
0.0174
Group velocity
0.045*c ns
100 7 . 5 @
MAX = g F v L
mrad
GeV t f
can be obtained if a 1.5 m long deflector is fed with 9 MW from the RF source
The filling time results: