Download 2016_10_06_ResonantKickerStatus

PAUL SCHERRER INSTITUTE
SwissFEL
Status of Resonant Kicker:
Sub-ppm shot-to-shot stability
M. Paraliev, C. Gough, S. Dordevic
Switchyard
Kicker chamber
(in-vacuum magnet)
SwissFEL layout
A
t
Current build-up in the
kicker magnet and bunch
extraction positions
PSI, 06.10.2016
Kicker resonator
Slide 1/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Overview
SwissFEL layout
Kicker 1 Kicker 2
Septum
Kicker system key parameters
Beam energy
Bunch separation
Total deflection angle
Number of Kickers
Deflection angle error
Total magnets length
Line field integral
Deflecting current
–
–
–
–
–
–
–
–
3 GeV
28 ns
1.8 mrad
2
80 ppm
1.5 m
10 mT.m
590 App
Switchyard
PSI, 06.10.2016
Slide 2/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Resonant Kicker Concept
I
L/2
Linac 2
L/2
C
Illustration of bunches separation using a resonant deflecting system
L
LL ctrl
C
Resonant technology
Driver
Vacuum
Simplified electrical circuit
56 ns
1st bunch
I (B)
500 Ap-p
t
Resonance build-up
PSI, 06.10.2016
2nd





No RL transient slope
No skin effect slope
Lower voltages (HV is enclosed in vacuum)
Solid state technology
Compact design

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
New driver technology
Complex amplitude measurement (ppm)
Demanding synchronization
Resonance frequency control
Ref.: M. Paraliev, C. Gough, “Development of High Performance
Electron Beam Switching System for Swiss Free Electron Laser at
PSI”, Proc. IPMHVC 2012, p. 691, San Diego, CA, USA, 2012
bunch
Slide 3/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Beam trajectory
Switch Yard
The two kickers K1 and K2
(together with the accompanying
dipoles D1, D2 and D3) provide
about 1.8 mrad deflection.
Adding the quads contribution the
effective deflection is reduced to
about 1 mrad.
Beam separation at the entrance
of the septum magnet is nominal 10
mm.
Field regions and beam trajectory in SwissFEL switch yard
Color rectangles represent the corresponding field regions
Q – Quadrupole magnet
Kx – Kicker magnet
Dx – Dipole magnet
S – Septum magnet
PSI, 06.10.2016
Slide 4/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Beam trajectory
Kickers’ region
The kickers K1 and K2 deflect
both bunches (“straight” and
“deflected”) vertically but in the
opposite direction.
Deflecting both beams results in
50% reduction of the required
magnetic field strength (respectively
the current in the magnets)
The three dipole magnets get the
“straight” beam back to its original
trajectory and increase deflection
angle of the deflected beam.
Beam trajectory in the kickers’ region
Color rectangles represent the corresponding field regions
Q – Quadrupole magnet
Kx – Kicker magnet
Dx – Dipole magnet
PSI, 06.10.2016
Slide 5/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Modes of operation
“Separation”
In “Normal” bunches separation mode, the bunches are
sent to the two beamlines.
The numbers above the magnets’ centers (dashed lines)
represent the relative deflecting strength of the particular
magnet.
Asymmetric configurations are also possible.
“Normal” separation mode
An “Alternative” separation mode makes possible to
keep the simultaneous operation of the two beamlines but
using only two “accompanying” dipole magnets.
The mode could be used for dipoles debugging.
“Alternative” separation mode
PSI, 06.10.2016
Slide 6/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Modes of operation
“One beamline only”
“Aramis only” mode
“Athos only” mode
In “One beamline only” modes both bunches are sent
to only one of the beamlines. The resonant kickers are off.
The alternative “Aramis only” mode could be used to
evaluate the stability of the DC “accompanying” dipole
magnets.
“Aramis only” alternative mode
PSI, 06.10.2016
Ref.: M. Paraliev, C. Gough, S. Dordevic, H. Braun, “High Stability Resonant
Kicker Development for the SwissFEL Switch Yard”, 36th International Free
Electron Laser Conference FEL 2014, MOP039, Basel, Switzerland, 2014
Slide 7/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Amplitude stability
Shot-to-shot (feedback off)
Averaged RMS
Two measurement systems working simultaneously
Precision measurement system 1 (PMS1)
Precision measurement system 3 (PMS3)
Stability PMS1
Stability PMS3
Noise floor PMS1
Noise floor PMS3
Stability Kicker*
Kicker system stab.*
= 8.0·10-7
= 8.1·10-7
= 6.2·10-7
= 6.4·10-7
= 5.0·10-7
= 3.5·10-7
Amplitude stability, ppm
* Calculated
1.6
PMS1 sigma100
1.4
PMS3 sigma100
Avrg(PMS1,PMS3) sigma100
1.2
Kicker sigma100 (calculated)
1
0.8
0.6
0.4
0.2
0
0
10
20
30
40
50
60
70
Time, s
Shot-to-shot stability of 100 consecutive pulses with feedback off (rep. rate 50 Hz)
PSI, 06.10.2016
Slide 8/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Amplitude stability
With feedback
“PMS1”, “PMS3” and “Full Range” have same scale.
PMS3
PMS1
Full Range
Stability degraded with time – why?
PSI, 06.10.2016
Slide 9/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Amplitude stability
Mains synchronization irregularity
“PMS1”, “PMS3” and “Full Range” have same scale.
PMS3
PMS1
Full Range
Irregular pulsing degrades stability due to the finite charging slope (~0.5 ppt/ms) of the main power module
storage capacitors.
(Tough compromise between precision and speed)
PSI, 06.10.2016
Slide 10/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Amplitude stability
Frequency effects (resonator tuning)
“PMS1” and “PMS3” have same scale.
(ppm)
Full Range
PMS1
PMS3
At resonance the dominant instability source is the mechanical vibration of the lid (thin sheet is used during
testing for convenience)
At ~13 ppm above resonance the detuning and the q-factor modulation cancel out and minimizing the
amplitude instability.
PSI, 06.10.2016
Slide 11/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Phase stability
0.01
0.01
Phase 18.0
Sigma100
15.0
00
12.0
Phase,
Deg
Phase, Deg
0.02
0.02
-0.01
-0.01
9.0
5 mdeg
-0.02
-0.02
6.0
-0.03
-0.03
3.0
-0.04
-0.04
Phase st. deviation, mDeg
RF Mixer and ADC based measurements
24 mdeg
0.0
020
10
25 20
30
30
40
35 50
40
60
Time, s
ADC based measurement
(averaged phase, pulse-to-pulse deviation)
RF Mixer measurement
(instantaneous phase, intra-pulse measurement)
The fast ADCs (16 bit, 250 MHz) of the Full Range amplitude measurement system digitize the sine
wave. The phase and the amplitude of the kicker’s current are measured using digital synchronous
detection. The values are averaged during the RF pulse to increase precision. The signal processing is
done by dedicated fast FPGA (Virtex-6) that sends the results to EPICS.
The ADC based phase measurement is limited by the ground vibration to ~5 mdeg.
The RF mixer based measurement gives an upper limit of the instantaneous phase noise ~24 mdeg.
PSI, 06.10.2016
Slide 12/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Phase stability
Considering multi bunch operation
Worst case (highest derivative) phase driven amplitude instability estimation:
180° (on-crest) operation, (two bunches separation)
- negligible - OK
45° operation** (four bunches separation)
- 62 (300) ppm – probably OK
90° operation** (three or five bunches separation)
- 87 (420) ppm – high!
**possible future operation modes
PSI, 06.10.2016
Slide 13/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
Expert panel
(to be implemented)
Kicker electronics
Driver
Self diagnostics
module
programmable
voltage regulator
20 bit resolution
SwissFEL
RF power
modules
Temperature
controlled
precision voltage
references and
regulators
Synchronization
Power
supplies
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High stability RF power modules (~ 5 kW peak @ 17.86 MHz)
Operational for only ~100 us @ 100 Hz - low average power ~ 50 W.
Four RF power modules in parallel.
Precision programmable (20 bit resolution) voltage regulator.
Self diagnostics module – device status (internal temperatures, interlocks, and etc.)
4U rack mount water cooled chassis
Designed and built in PSI.
PSI, 06.10.2016
Slide 14/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Kicker electronics
Expert panel
(To be implemented)
Precision amplitude measurement system
Low noise difference
matrix amplifier/detector
10 bit 40 Ms/s ADC
and FPGA module
Balancing unit
and input limiter
Power supply
(Bottom side)
Precision 20 bit
programmable
current source
Temperature
controlled
reference
voltage source
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DC/DC converters,
regulators, filters and
self diagnostics module
(Bottom side)
Resolution ~0.3 ppm, noise floor ~0.6 ppm, range ± 150 ppm
Fast recovery (<10 ns) analogue input limiter – withstanding 10000% overload
High stability programmable (20 bit resolution) current source - 2 A (for balancing)
Self diagnostics module – device status (internal temperatures, supply voltages and etc.)
2U rack mount water cooled chassis
Designed and built in PSI.
PSI, 06.10.2016
Slide 15/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Kickers
Mechanical design
The tanks for the three identical systems
are delivered.
Vacuum tank
The resonators are in production. There
were delays mainly due to some difficulties
associated with the ceramic details’ brazing.
The parts should be ready next month.
Resonator
PSI, 06.10.2016
Slide 16/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Lambertson septum
Mechanical design
Solenoid
Iron core
Air
St. steel
plate
Longitudinal field (0.001Hz)
Vacuum
3D simulation model
Alu ring for high frequency
field components
suppression
Transverse field
(higher frequency suppression)
 Half-in-vacuum design
 Deflection 35 mrad
 High frequency field components suppression
Designed in PSI.
PSI, 06.10.2016
Slide 17/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Conclusion
A novel concept for bunches separation using a resonant kicker magnet was developed
and evaluated. A prototype of the resonant kicker was designed and built together with
dedicated driver and monitoring system.
A slow feedback SW application (C code) controls the system using EPICS channel
access protocol.
Since the shot-to-shot stability is crucial for this novel concept to work, the stability of
the prototype system was extensively evaluated:
 Shot-to-shot amplitude stability (feedback ON): ~1.5 ppm rms
 Shot-to-shot amplitude stability (feedback OFF): ~0.8 ppm rms
 Shot-to-shot phase stability: RF pulse average ~5 mdeg ( instantaneous <24 mdeg)
 Shot-to-shot phase driven amplitude instability: <0.1 ppm
The achieved stability levels open possibilities for separating more bunches in future.
PSI, 06.10.2016
Slide 18/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Additional material
PSI, 06.10.2016
Slide 19/18
Presented by M. Paraliev
PAUL SCHERRER INSTITUTE
SwissFEL
Additional material
Derivation
PSI, 06.10.2016
Slide 20/18
Presented by M. Paraliev