IOTA BPM System Overview Nathan Eddy IOTA BPM
IOTA BPM System Overview Nathan Eddy IOTA BPM Review 3 January 2019
IOTA has 21 BPMs 2 Nathan Eddy | IOTA BPM System Overview 01/03/2019
Simple System Cartoon Analog Transition Modules ACNET Position Intensity Raw ADC Control Status 3 LLRF & Timing RF Ref Turn Marker DAQ Front-End Triggers Ethernet Nathan Eddy | IOTA BPM System Overview 01/03/2019
BPM Pickups • There are 20 standard button style pickups – 47. 5 mm inner diameter – 11 mm diameter button electrodes – Same pickup used in the FAST Linac • There is one wide apperture button style pickup designed for injection at A 1 C – 76 mm innder diameter – 20 mm diameter button electrodes 4 Nathan Eddy | IOTA BPM System Overview 01/03/2019
BPM Pickup Measurements • Button response was measured using a test fixture with a strip line attached • Each style was also measured via stretched wire and the response fit to a 2 D polynomial to linearize the pin cushion effect of the buttons 5 Nathan Eddy | IOTA BPM System Overview 01/03/2019
Transition Modules • Based off FAST BPM architecture • Control Module – CAN Bus interface – Control Input attenuation for ATMs from 2 -33 db • Analog Transition Module – Provide bunch by bunch signal conditioning – 4 channels (1 bpm) per module – Up to 20 per crate – New design 6 Nathan Eddy | IOTA BPM System Overview 01/03/2019
Analog Transition Modules • Provide a signal conditioning before digitization for each bunch from the button electrode (New Design) – Short doublet from button electrode (3 ps to 1 ns) – 30 MHz RF Bucket -> 33 ns • RF Section – set signal level into RF Detector • RF Detector – envelope option for ADL 5511 plus LPF • Output Section – Provide further gain and offset 7 Nathan Eddy | IOTA BPM System Overview 01/03/2019
Analog Transition Module Testing 8 Nathan Eddy | IOTA BPM System Overview 01/03/2019
Data Aquisition Front-End • Based off FAST BPM architecture • VXS/VME Crate • Digitizer Modules – digitize signals for each electrode and perform DSP to measure magnitude (new design with JESD-204 b fast serial) • Timing Module – provides clock and trigger information to all Digitizer Modules • Controller – commercial x 86 processor board running real time linux with custom kernel (new operating system) 9 Nathan Eddy | IOTA BPM System Overview Controller Timing Module 11 Digitizer Modules 01/03/2019
Timing and Trigger Module • Custom design developed for bpm applications – a lot of flexibility • Custom firmware for IOTA BPM system – Use serial trigger signal to encode trigger type – Provide central source for arm/control/trigger for all digitizer modules 10 Nathan Eddy | IOTA BPM System Overview 01/03/2019
Digitizer Modules • Custom Digitizer Modules – 250 MS/s 16 bit ADCs – JESD-204 b fast serial interface – Altera Aria V FPGA with 24 dedicated fast serial links – Dedicated clock management – 512 Mbytes of DDR 3 memory – VME/VXS/Gig. E capable • Custom firmware using Altera QSYS integrated system – ARM CPU, bus, interfaces – DSP module for raw ADC and magnitude calculation 11 Nathan Eddy | IOTA BPM System Overview 01/03/2019
Digitizer DSP • ADCs locked to RF – 240 MS/s – 8 samples per bunch – 32 samples per turn – 64 sample (2 turns) delay adjustment on each channel • Dual 256 MB DDR 3 Banks – 1 Bank for raw ADC – 1 Bank for DSP magnitudes – Customize buffers for different triggers 12 Nathan Eddy | IOTA BPM System Overview • Calculate Magnitude for each bunch – Currently use 2 pt at peak and 2 pt for background (2 x 2) – Track background for each bunch – Use highest S/N samples – Can average each bunch up to 255 turns 01/03/2019
System Controller • • Commercial x 86 VXS/VME processor module Running real-time linux rather than Vx. Works Setup for Timing Module and Digitizer Modules Readout of Digitizer Module Data – Raw ADC, Bunch Magnitudes • Calculate position and intensity for each bunch – Position as 2 D 7 th order polynomial – Intensity as sum of 4 magnitudes • ACNET interface – Array Devices for each bpm (2048 elements) • Horizontal Position, Vertical Position, Intensity (Sum) – Raw ADC readback up to 65 k samples per bpm – Arm/Trigger Control • Backdoor interface – Custom interface which allows diagnostic module access – Large data readback 13 Nathan Eddy | IOTA BPM System Overview 01/03/2019
IOTA BPM System Current Status • At startup had limited diagnostic software – – Limited resources for software development No backdoor available on linux front-end Implementing Backdoor helped a lot! Continue to work on ACNET improvements • Startup plagued by small signals -> S/N issues – Typical currents of 600 -200 m. A at injection and falling – Bunch length was also varying from 1 ns to several ns – Switched to 2 x 2 magnitude calculation and average bunch magnitudes for 255 turns to allow orbit measurements on – Installed pre-amps with 32 db of gain in the tunnel on 7 bpms 14 Nathan Eddy | IOTA BPM System Overview 01/03/2019
IOTA BPM System Raw Signals No pre-amp With pre-amp • Data taken just before shutdown (12/21) with 500 m. A • Transition Attenuation Settings – Minimum attenuation (2 db) without pre-amp – Full attenuation (33 db) with pre-amp • See double the signal in bpms with pre-amps 15 Nathan Eddy | IOTA BPM System Overview 01/03/2019
IOTA BPM System Turn by Turn No pre-amp 16 Nathan Eddy | IOTA BPM System Overview With pre-amp 01/03/2019
IOTA BPM System Orbit Sample @29. 4 k. Hz No pre-amp Sample @29. 4 k. Hz With pre-amp • Average each bunch for 255 turns, can further average 2048 returned values offline (mm level resolution @600 m. A) • Can see synchrotron oscillations (3600 turns, 2. 1 k. Hz) 17 Nathan Eddy | IOTA BPM System Overview 01/03/2019
IOTA BPM System Orbit No pre-amp With pre-amp • Averaged Orbit measurements over 30 minutes • See position shift with intensity on all bpms 18 Nathan Eddy | IOTA BPM System Overview 01/03/2019
RF Detector Non-Linearity • Looked closer at Transition Module test data • Clearly see non-linearity when plotted as ratio of input to output • The response can be fit very well 19 Nathan Eddy | IOTA BPM System Overview 01/03/2019
Fit For Non-linearity Correction • Can correct magnitude for non-linearity • Need ratio of measured to true to be fixed – Currently with 2 x 2 depends on synchrotron phase… 20 Nathan Eddy | IOTA BPM System Overview 01/03/2019
IOTA BPM System Summary • Initial performance of the system was not as expected • Mitigating Factors – Late design change to provide single 33 ns bucket measurement – New digitizer design required more testing than expected for JESD-204 b interface – Issues with Booster BPM System impacted software resources • Started with very limited system software modified from Booster • Growing pains with new linux platform • Performance is improving – TBT measurements within spec for 1 m. A of beam current – Adding pre-amps should provide performance down to 100 m. A – Plan for calibration to linearize RF Detector response 21 Nathan Eddy | IOTA BPM System Overview 01/03/2019
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