1. Undulator Cavity BPM Status
May 27, 2019
Undulator Cavity BPM Status

2. Design Review Outline
BPM System Design Overview
Cavity Design
Electronics and ADC
Current status for phase I prototype testing
Planning phase II prototype test
First article and production

3. LTU and Undulator BPM System Specification
Parameter
Specification Limit
Condition
Resolution
< 1m
0.2 – 1.0 nC
+/- 1 mm range
Offset Stability
< +/- 1m
1 hour
20.0 +/ Celsius
< +/- 3m
24 hours +/- 1 mm range
Gain Error
< +/- 10 %
Dynamic Range, Position
+/- 1 mm
10 mm diameter vacuum chamber
Dynamic Range, Intensity
> 14 dB
PC Gun

4. BPM System Overview Block Diagram

5. X-Band Cavity BPM Design
Each BPM has position cavity and reference cavity
SLAC selective coupling design utilized to reduce monopole mode
Iris couplers are precisely EDM into Solid Copper Body
Waveguide transition brazed to body

6. Cold Test Prototype Non-vacuum cold test prototype
Accelerated design verification and cold test development
Removable end caps
Presently used to verify tuning effects and test fixture development

7. Before and After Brazing (ITS Prototype)

8. Prototype Cold Test (Dipole cavity 500 micron offset)
Parameter
(500 µm offset)
Predicted
Measured Prototype # 1
bolted end caps
Measured Prototype # 2 brazed end caps
Frequency TM010
8.262 GHz
8.271 GHz
8.243 GHz
Coupling TM010
-53 dB
-69 dB
-62 dB
Frequency TM110
GHz
GHz
GHz
Coupling TM110
-32 dB
-28 dB
-24 dB
Q (loaded) TM110
2704
2086
2391
X/Y Isolation TM110
-26 dB
-33 dB
-23 dB
Dipole to Monopole cavity Isolation
<-80 dB
<-85 dB
<-89 dB
Frequency TM020
GHz
GHz
GHz
Coupling TM020
-78 dB
-64 dB
-50 dB

9. Baseline Design for Phase I Prototype Miteq X-Band Low Noise Receiver
Existing product line
WR 75 Waveguide Interface
Low Noise Figure (2.7 dB)
Budgetary price for (3 channels) $

10. Prototype Receiver Specification
Parameter
Specification Limit
Condition
RF Frequency
GHz
20.0 +/ Celsius
Dx, Dy, Intensity
Input Peak Power
50 watts peak
No damage (limiter protection)
LO Frequency
GHz
(2856 MHz*4)
1nC, 1mm offset, 200fs BL
LO Power Range
+10 dBm Max.
Provide LO for 3 down converters
IF Frequency
60 MHz Min.
Noise Figure Dx and DY
2.7 dB Max.
Noise Figure Intensity (reference)
4.0 dB Max.
LO to RF Isolation
40 dB Min.
LO to IF Isolation
45 dB Min.
Output Power
+14 dBm
1 dB compression
Conversion Gain
25 dB typical

11. In-Tunnel Receiver Block Diagram

12. Prototype X-Band Low Noise Receivers
Conversion gain 28 dB
Over 60 dB dynamic range
Noise Figure 2.5 dB
IF bandwidth MHz
Receiver noise floor -88 dBm assuming 20 MHz IF bandwidth
Cavity BPM Sensitivity:
-54 dBm/0.2nC/1m

13. BPM System Test Approach
Phase I
Injector Test Stand ITS
Install single X-Band Cavity and modified off-the-shelf down converter receiver
Mount BPM on two-axis translation stage
Phase II
LEUTL test with PC gun
Install three X-Band Cavities BPMs
Mount all 3 BPMs together on a two-axis translation stage

14. Injector Test Stand (ITS) Beam Parameters
Charge- 1 nC single-bunch
Bunch length- ~ ps FWHM for ps laser
Spot size on final screen at 5.5 MeV ~ 0.75 mm rms, ps laser

15. (Phase I) ITS BPM Test Results
BPM setup on X/Y translation stage
Aligned BPM Pitch and Yaw to < 25 m
Initial beam spot size 2-3 mm rms at low charge (0.05 nC) at faraday cup before adding new focusing magnets to reduce to 200 um rms
Beam stability limited to 50 m rms. Laser improvements ongoing

16. ITS Data Processing Development
Cavity BPM and electronics tested using ITS beam line
First raw cavity voltage outputs captured on scope 6/9/06
Mover system calibration
Testing is on-going following Aug/Sep shut-down
Hor.
Ref.
Vert.

17. ITS Data Processing Development

18. Waveforms acquired with sampling scope and processed via Epics

19. Normalized waveforms 0.05 nC charge

20. Dipole Cavity Preliminary Test Data
Parameter
Predicted Value
Cold Test Data
ITS Test Data
Frequency (TM110)
GHz
GHz
GHz
Q (loaded) (TM110)
2704
2391
2500
Isolation X/Y (TM110)
-26 dB
-23 dB
< -20 dB
Voltage Output
2.3 mV/um/nC
1.22 mV/um/nC

21. (Phase II) 3 BPM Test Schedule Milestones
Refine design and develop First Article Cavity BPM and support hardware
August 06
Start 3 BPMs
October 06
First unit with accelerated delivery
Install 3 cavity BPMs into APS LEUTL and Test
December 06

22. Prototype Phase II Cavity BPM Specification
Parameter
Specification Limit (change)
Condition
TM110 Frequency
Dipole Cavity
GHz
( GHz)
20.0 +/ Celsius
Loaded Q factor
3000 +/- 200
(3500 +/- 200)
Power Output TM110
-10 dBm
1nC, 1mm offset, 200fs BL
X/Y Cross Talk
< -20 dB
(<-26 dB)
+/- 1 mm range
TM010 Frequency
Monopole Cavity
( GHz)
3000+/- 200
Power Output TM010
1nC, +/-1mm offset range, 200fs BL

23. Dipole Cavity Design Beam pipe radius = 5 mm
Cavity radius = mm ( mm)
Cavity gap = 3 mm
Distance beam axis to bottom of wg = 9.5 mm (10.5 mm)
Waveguide= x 3 mm

24. Monopole Cavity Design
Beam pipe radius = 5 mm
Cavity radius = mm ( mm)
Cavity gap = 2 mm (3 mm)
Coupling Slot = 2 x 4 mm (2.5 x 4 mm)
Tangent to surface of cavity opening to bottom of waveguide=1.734 mm (3.75 mm)
Waveguide= x 3 mm

25. Tuning Pins Feature Added
Tuning pins prototyped and tested in lab
Tuning pin simulations verify lab measurements
Tuning pins will improve performance and production yield
Tuning Pins

26. Design Development
First Article Design
ITS Test Unit
Cold Test Unit

27. Receiver Design Changes
Packaged 3 channel receiver
High/Low gain feature (28/0dB) to extend dynamic range.
Add a simple CW tone self-test feature

28. Receiver Packaging Design
Receiver enclosure 12.5 wide by 11 deep by 2.5 thick (inches) with radiation shield cover
Houses input filters local oscillator and down-converter
3-WR75 Inputs, 3-type “N” outputs, LO ref. input Type “N”, power and control cable

29. SLAC ADC Development
The PAD (Phase and Amplitude Detector) being considered for Cavity BPM ADC
Linear Technologies LTC bit digitizer chip specified to run up to 130MHz

30. Phase II Data Acquisition Design Approach
Instrument three BPMs with SLAC Built 16-bit, 130 MSPS digitizers (PAD)
Epics driver available
Synchronize ADC clock with 119 MHz
Digitize horizontal, vertical position and Intensity 0 to 1 volt range
Digital down convert 40 MHz IF decaying exponentials

31. Phase II Testing Objectives 3 BPM Test
Test three BPM separated by fixed distance to determine single-shot
Evaluate First Article Prototypes
Complete test matrix to prove compliance to specification

32. System Layout and Planning
Beam
X-band receiver LRU

33. Production Phase
Production of 2 BPMs for LTU 04/07
Production of 6 BPMs for undulator 04/07
Production of 9 BPMs for undulator 06/07
Production of 9 BPMs for undulator 08/07
Production of 10 BPMs for undulator 10/07
Spares 12/07

34. X-Band Cavity BPM development ongoing
Summary
X-Band Cavity BPM development ongoing
Bolt-together prototype (non-vacuum) complete
ITS prototype testing ongoing
3 BPM test prototype design enhancements ongoing
Receiver Prototype Development
First Prototype installed in ITS with good results
3 BPM test prototype design incorporates high/low gain, self-test and final packaging
Data Acquisition and Test
Collaborating with SLAC to use the same ADC as SLAC LINAC BPM upgrade