BIW 2006 Simultaneous Tune and Coupling Feedback during RHIC Run 6 Peter Cameron.
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Transcript of BIW 2006 Simultaneous Tune and Coupling Feedback during RHIC Run 6 Peter Cameron.
BIW 2006
Simultaneous Tune and Coupling Simultaneous Tune and Coupling Feedback during RHIC Run 6Feedback during RHIC Run 6
Peter Cameron
BIW 2006
BIW 2006
AcknowledgementsAcknowledgements• Tom Shea – the foundation and foresight• Mike Harrison, Steve Peggs, Alex Ratti
– US LHC Accelerator Research Program• RHIC HF Instrumentation
– Earlier efforts• BNL C-AD Instrumentation – Tom Russo et al
– The present effort
BIW 2006
OutlineOutline• System Architecture• Direct Diode Detection (3D) AFE• Eigenmodes, set and measured tunes,…• Coupling and de-coupling
– essential for tune feedback• Ramping with and w/o feedbacks• 3D AFE ‘Beam Noise’ Susceptibility• Plans
BIW 2006
BIW 2006
BIW 2006
10nm
BIW 2006
x
y
Q1
Q2
A1,xA2,x
A1,y
A2,y
x
y
Q1
Q2
1,x
1,y
2,x
2,y
x
y
Q1
Q2
A1,xA2,x
A1,y
A2,y
x
y
Q1
Q2
A1,xA2,x
A1,y
A2,y
x
y
Q1
Q2
1,x
1,y
2,x
2,y
eigenmodes rotated wrt horizontal and vertical planes
due to coupling.
special case general case
BIW 2006
Set and Measured TunesSet and Measured Tunes• Measured tunes
– The ‘eigenvalues’ – physical observables– Rotated from H and V by coupling
• Set tunes– What tune would be in the absence of coupling– dQmin – forbidden zone
• complicates tune control without feedback• breaks feedback
– can be calculated with knowledge of coupling
BIW 2006
Set and Measured TunesSet and Measured Tunes
set measured
yxxy
y
x
y
x
x
y
x
y
dd
C
AA
rC
AA
r
,2,22,1,11
,2
,22
,1
,11
,
,2
,2
21
2121
21
212122
11
,1
2,
21
rrrrQQ
rrQQrr
CC
2221
21
20,
2221
21
10, , CQQCQQ yx
set measured
BIW 2006
tune feedback would break here
BIW 2006
Manual DecouplingManual DecouplingSkew chrom
0
Chrom measurement
BIW 2006
dQmin < .001
BIW 2006
BIW 2006
Coupling Echoes Coupling Echoes
½ synchrotron period
1 sec
Coupling coefficient ‘C’
0
.02
BIW 2006
OutlineOutline• System Architecture• Direct Diode Detection (3D) AFE• Eigenmodes, set and measured tunes,…• Coupling and de-coupling
– essential for tune feedback• Ramping with and w/o feedbacks• 3D AFE ‘Beam Noise’ Susceptibility• Plans
BIW 2006
First Ramp with FeedbacksFirst Ramp with Feedbacks
BIW 2006
First Ramp with Feedbacks 2First Ramp with Feedbacks 2
BIW 2006
Last Blue Ramp with FeedbacksLast Blue Ramp with Feedbacks
BIW 2006
Next Ramp with Feedbacks OffNext Ramp with Feedbacks Off
BIW 2006
Beam NoiseBeam Noise• Steve Peggs –
“declare Victory”• Peter Cameron –
“Mission Accomplished”
• One messy little detail– 3D AFE sensitivity to
‘beam noise’– No free lunch
BIW 2006
3D AFE ‘beam noise’3D AFE ‘beam noise’• Beautiful when looking at amplitude
– Very sensitive ~10nm– Resistant to dynamic range problems (bunch length, beam
offset,…)• But, when you put it in a phase loop…. • Possible sources
– Beam loss– High frequencies - longitudinal ‘hot spots’– Low frequencies
• quadrupole cryostat vibrations• mains harmonics
– Instabilities (weak – not noticed by anything except 3D AFE)– Long range beam-beam
BIW 2006
Immediate plans Immediate plans • Further investigation of ‘beam noise’, and
how to cope with this• Chromaticity measurement and feedback• Movement of the system into the CERN
architecture – DAB board
BIW 2006
Conclusions Conclusions • World’s first implementation of
simultaneous tune and coupling feedback is successful
• The door remains open for simultaneous tune, coupling and chromaticity feedback at LHC
BIW 2006
Back-up slides Back-up slides
BIW 2006
3D on the Ramp - 1 Jan 05
dominant spacing is 180Hz
60Hz onset60Hz end
IPM every100 turns(780 Hz)
BIW 2006
• Transverse instability• Not fixed by chrom• Frequently present at a
level not detectable by anything other than BBQ
• Upper half of sideband
BIW 2006
Summary of Chromaticity
t
t
vert
horiz
+5
-5
dp/p of +/-10-4 gives ~+/-100 radial modulation (RHIC&LHC)
-5
-5
+5
+5
Q'
Q'
Q'ramp 6380
ramp 6382
ramp 6381
in RHIC modulation is at 1Hz
chrom - good results under sequencer control