1 c. simon clic instrumentation workshop bpm development @cea/irfu c. simon on behalf of the...
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1C. Simon CLIC Instrumentation workshop
BPM development @CEA/Irfu
C. Simon on behalf of the Saclay’s group
CLIC Instrumentation workshop
2nd - 3rd June 2009
202/06/09 CLIC Instrumentation workshop
Introduction
CEA/Irfu is developing two types of BPMs based on a radiofrequency reentrant cavity:
• The first monitor is developed for the CLIC Test Facility (CTF3) probe beam CALIFES at CERN:
- is operated in single bunch and multi-bunches modes. - single bunch resolution potential < 1 µm
• The other BPM developed for the XFEL (Thirsty of those monitors will be installed in XFEL cryomodules) :
- has an aperture of 78 mm - is designed to work at cryogenic temperature in a clean environment - can get a high resolution and the possibility to perform bunch to bunch measurements.
One prototype is installed in a warm part in the Free electron LASer in Hamburg (FLASH), at DESY.
302/06/09 CLIC Instrumentation workshop
CALIFES linac
6 BPMs are installed on the CALIFES linac
15 MV/mcompression
17 MV/macceleration
17 MV/macceleration
LIL sections
beam dump
Focusing coils
K
quadrupoles
LaserRF pulse compression
2 x 45 MW
10202525
Profile monitor
Beam position monitor
Steerer
RF gun cavitySpect. magnet RF deflector
SpecificationsEnergy ~ 170 MeVEmittance < 20 .mm.mradCharge per bunch : 0.6 nCEnergy spread: <2%Number of bunches : 1- 32 – 226
Bunch charge (single/multi bunch): 0.6 nC/ 6 nC/NbBunch length (rms) : 0.75psInitial /final bunch spacing :5.3/1.8 ps, 1.6/0.5 mmTrain length: 21 - 150 nsTrain spacing (rep. rate): 5 Hz
402/06/09 CLIC Instrumentation workshop
Reentrant Part
Reentrant Cavity BPM for CALIFES
Bent coaxial cylinder designed to have:
-a large frequency separation between monopole
and dipole modes
- a low loop exposure to the electric fields
• The cavity is fabricated with titanium and is as compact as possible :
~125 mm length and 18 mm aperture 4 mm gap
Eigen modes
F (MHz) Ql (R/Q)l (Ω) at 5 mm
(R/Q)l (Ω) at 10 mm
Measured Measured Calculated Calculated
Monopole mode
3988 29.76 22.3 22.3
Dipole mode
5983 50.21 1.1 7
Due to mechanical tolerances, dipole mode frequencies are different for each BPMs, 100 MHz IF frequency is, therefore, used so that monitors operate in single and multi-bunch modes.
502/06/09 CLIC Instrumentation workshop
Signal Processing for CALIFES BPM Hybrids installed close to BPMs in the CLEX
Multiport switches used to have one signal processing electronics to control six BPMs.
Analog electronics with several steps to reject the monopole mode
BPMs in the probe beam linac tunnel
beam positionmonitor 1
x1
x2
y2
y1
180°hybrid
180°
hybrid
phaseshifter
3 dBcombiner
beam positionmonitor 6
x1
x2
y2
y1
180°hybrid
180°
hybrid
3 dBcombiner
.
.
.
6 to 1multiportswitch
phaseshifter
x
y
6 dB
6 dB
18 dBm leak.
18 dBm leak.
Filter 5997 MHz600 MHz BW
0 to 70 dB
0 to 70 dB
18 dBm leak.
Lowpass Filter120 MHz
0 to 70 dB
3 dBsplitter
reference2.891 GHz
14 dBm
RF electronics in the hall
8channel
videoamp
Gv = 10
4channel10 bits2 Gs/sADC
2channel10 bits2 Gs/sADC
DAQ in the hall
control unit
VME Crate
signals for switchesand variable
attenuators control
Ix
Qx
Iy
Qy
Filter 5997 MHz600 MHz BW
RF
LO
II-Q
demodulator
Q
RF
LO
II-Q
demodulator
Q
Lowpass Filter200 MHz
Filter 3990 MHz400 MHz BW
AcqirisDigitizers
Hybrid
couplers
RF electronics used synchronous detection with an I/Q demodulator.
602/06/09 CLIC Instrumentation workshop
Control Command of BPMs1/Sampling with acqiris boards and readout signals on OASIS
3/Results sent on graphic windows under JAVA and in a file to be used with Matlab
6 BPMs implemented
sincos QI
2/Signal processing: Digital Down Conversion
- raw waveform multiplied by a local oscillator of the same frequency to yield a zero intermediate frequency - real and imaginary parts of each IF are then multiplied by a 60 coefficient, symmetric, finite impulse response (FIR), low pass filter with 40MHz 3dB bandwidth
P
A
Qsin
22 QIA
Beam position
A
Icos
702/06/09 CLIC Instrumentation workshop
Signals read with Oasis viewer (1)
channels
Good transmission behind the first section
802/06/09 CLIC Instrumentation workshop
Signals read with Oasis viewer (2)
Visualisation of I/Q signals on the X and Y channels
902/06/09 CLIC Instrumentation workshop
Cold Reentrant BPM for the XFEL
quadrupole
BPMbellows
HOM absorber
gate valve
XFELX-Ray Free-Electron Laser
Specifications
Single bunch resolution (RMS): 50 µmDrift over 1 hour: 5 µmMax. resolution range: +/- 3 mmReasonable signal range : +/- 10 mmLinearity: 10%
Transverse alignment tol. (RMS): 300 µmCharge dependence : 50 µm
1002/06/09 CLIC Instrumentation workshop
XFELX-Ray Free-Electron LaserCold Reentrant Cavity BPM for the XFEL (1)
Twelve holes of 5 mm diameter drilled at the end of the re-entrant part for a more effective cleaning.
CuBe fingers to put in contact feedthrough and cavity
• 30 reentrant cavity BPMs will be installed in XFEL cryomodules
Eigen modes
F (MHz) Ql (R/Q)l (Ω) at 5 mm
(R/Q)l (Ω) at 10 mm
Measured Measured Calculated Calculated
Monopole mode
1255 23.8 12.9 12.9
Dipole mode 1724 59 0.27 1.15
1102/06/09 CLIC Instrumentation workshop
XFELX-Ray Free-Electron LaserCold Reentrant Cavity BPM for the XFEL (2)
• February 2009, a first prototype was sent to DESY to be installed in a cyomodule test
• Few problems are appeared but were resolved:
• One of flange was re-manufactured
• One of antennae was not in contact with the BPM CuBe contact was therefore moved
• Finally, the prototype was assembled to the quadrupole
• The “cold reentrant BPM” passed leak test and high pressure rinsing
1202/06/09 CLIC Instrumentation workshop
Signal processing for the cold reentrant BPM• Hybrids will be installed in the tunnel
• Signal processing electronics uses a single stage down conversion
XFELX-Ray Free-Electron Laser
• RF front-end electronics based on an PCB with surface mount components
• Digital electronics designed by PSI
BPMs in the linac tunnel
beam positionmonitor
x1
x2
y2
y1
180°hybrid
3 dBcombiner
x
y
Qx
ADC
Digital board
Ix
Qx
Iy
Qy
180°
hybrid
Ix
Qy
Iy
Low passFilter 65 MHz
Low passFilter 65 MHz
PLL
reference10 MHz1 Vpp
RF front-end
Band pass filter1724 MHz
110 MHz BW
Amplifier
Isolator
Isolator
Detector
Isolator
LO
RF
LO
RF
90°hybrid
LO
RF
LO
RF
90°hybrid
Mixer
Mixer
3 dBsplitter
3 dBsplitter
3 dBsplitter
Phaseshifter
VideoAmplifier
Attenuator
Attenuator
control unitTo pilot
attenuators, switchs
PLL
3 dBsplitter
Attenuator
reference10 MHz1 Vpp
3 dBsplitter
Band pass filter1724 MHz
110 MHz BW
Band pass filter1250 MHz
110 MHz BW
1302/06/09 CLIC Instrumentation workshop
RMS resolution: ~4 µm on the Y channel
~8 µm on the X channel
XFELX-Ray Free-Electron LaserBeam Studies
Good linearity in a range ± 12 mm
with 1 nC and dynamic range +/- 5 mm
Possibility bunch to bunch measurements100 bunches read by the reentrant BPM
Damping time (Cavity): 9.4 ns
Time resolution (Cavity + electronics): ~40 ns
• Beam tests carried out with the room temperature reentrant BPM on the FLASH linac
• Simulated resolution with 1 mm beam offset: < 1 um
20 ns
20 mV
40 ns
IF signal behind Lowpass Filter on
channel Δ
1402/06/09 CLIC Instrumentation workshop
Summary
Reentrant cavity BPM at CALIFES:
• Operated in single and multi-bunches
• Final signal post-processing and interface Java applications are under development and should be tested during the next beam time
• Need beam time to calibrate BPMs and determine resolution
Reentrant cavity BPM for the XFEL:
• First prototype was assembled to the quadrupole for a XFEL cryomodule test
• PCB of the RF front-end Electronics designed to reduce the electronics cost
• Circuit is in the making and we need to test it soon…
Thank you for your attention