kirsten hacker triggering and measurement devices for lcls undulator…[email protected]...

Kirsten Hacker

Triggering and Measurement Devices for LCLS Undulator… [email protected]

10/14/04 1

Triggering and Measurement Devicesfor the LCLS Undulator Test Bench

Kirsten Hacker

October 14, 2004

Kirsten Hacker


10/14/04 2

A basic triggering setup

TriggerGeneration

Every ~100th edge

DeviceWith <40,000

Memorylocations

Quadrature Signal

TTL

every 1 um for 3 m3,000,000 edges

Linear scalewith

encoder read head

Kirsten Hacker


10/14/04 3

Triggering problemsCarriage pitch and yaw => if you trigger on every nth edge, you will generate triggering errors

1um

Kirsten Hacker


10/14/04 4

Triggering problemsCarriage pitch and yaw => if you trigger on every nth edge, you will generate triggering errors

1um

Kirsten Hacker


10/14/04 5

A

B

Z

Position changeDirectionRecord of triggered positionsUse index pulses on linear scale to start and stop trigger generation

Single triggers for specified positionsover a specified distance

Kirsten Hacker


10/14/04 6

Triggering solutions

Design an electrical circuit to generate single triggers for specified positions

Design software that executes on an FPGA to generate single triggers for specified positions (and record those positions)

Joseph Xu, ANL

Kirsten Hacker


10/14/04 7

Triggering solutions

Design an electrical circuit to generate single triggers for specified positions

Design software that executes on an FPGA to generate single triggers for specified positions (and record those positions)

Joseph Xu, ANL

Kirsten Hacker


10/14/04 8

FPGA benefits

Easy to change and expand (x,y,z,…)

Easy to interface with process control software

Programmed with LabView (quick learning curve)

Kirsten Hacker


10/14/04 9

Connector2/DIO0

Index Count

032 bit

Reset

EndState

# indicesAbsolute Position

1000

Bad Index Count

Index Save

counts/indx

True False

EndState

0 Tr

Count Status

counts/indx

Relative Position

# indices

Reset

Relative Position

4

Rising Edge Event Counter

0

0

1

-1

Connector2/DIO5Connector2/DIO6Connector2/DIO7Connector2/DIO8

0

multiples of True

1 0

50 True 50

100

Reset

0

2

EndState

Absolute Position

Start Position True

Relative Position False

Reset

EndState

00

Reset Toggle

True

indx before reset

counts/indx

Connector2/DIO2Connector2/DIO1Connector2/DIO0

32 bit, save on index, index : A,B,Z all low, quadrature counter

00

032 bit

Output Count

032 bit

Connector2/DIO7

Reset

multiples of Check CountBad Outputs

Output Status

Relative Position

Rising Edge Event Counter

# indices

0

0

0

1 [0..1]

Executes in parallel

Checks for change in digital signal at > 40 MHz

Compares input digital status to previous loop iteration’s digital status

Kirsten Hacker


10/14/04 10

FPGA requirements

Operates at more than 40 MHz so carriage must move slower than 10 m/s on a linear scale with micron resolution to avoid aliasing

Encoder signal must have low electrical noise

Noise spikes could be interpreted as position changes

Kirsten Hacker


10/14/04 11

Electrical noise reduction

Use motor driver that doesn’t generate DC with chopping (special low-noise drive)Use low-noise power supply and minimize cable lengths for encodersAdditional measures could include:

Adding a Schmitt triggerUsing a comparator with differential signalsUsing a line driver to reduce noise picked up on long cable

Kirsten Hacker


10/14/04 12

Test setup

Quadrature Signal

TTL

every 1 um for 3 m3,000,000 edges

DeviceWith <40,000

Memorylocations

FPGA moduleProgrammedWith LabView

PXI CrateRunning LabView

PCRunning

LabWindowsProcesscontrol

File-sharing

Measured Signal

Trigger

GPIB

Kirsten Hacker


10/14/04 13

Successful triggering system tests

Count lines on linear scale and get expected number

Sample function generator input and get expected number of cycles

Record every position for which a trigger was generated and write it to a file

Kirsten Hacker


10/14/04 14

Measurement System

Hall Probe

CoilA=0.2 m^2

HP3458multimeter

HP3458multimeter

+-

FPGATriggers

Pre-ampG=1000

10 meter cable

10 meter cable

Capacitive Distance Sensor

Synchronized VoltageSampler

Linear Scale Encoder

∫

Carriage

Kirsten Hacker


10/14/04 15

Measurement System

Hall Probe

CoilA=1.2 m^2

HP3458multimeter

HP3458multimeter

+

-

FPGATriggers

Pre-ampG=1000

10 meter cable

10 meter cable

Capacitive Distance Sensor

Synchronized VoltageSampler

Linear Scale Encoder

∫

Carriage

Kirsten Hacker


10/14/04 16

Hall probe comparison

Measurements taken withprobes in zeroing chamber

Sentron AG 2MR-48/3B (ANL)Bell Series 9900 (DESY) with aluminum probeGroup 3 - 141 with 141 probeGroup 3 – 151 with 141 probe

Sentron XSentron YBellGroup 3

Specification from first field integral1e^-5 T

Kirsten Hacker


10/14/04 17

Coil measurements

voltmeter

voltmeter

Gain=1000

10 meter BNC cable

500 ohm ~resistance of coil

Field Tolerance = 1e^-5 T

Flux = Field * Area = 2e^-6 V*s

Flux tolerance = 2e^-6 V*s

From the integrator

∫

∫

.2 m^2 ~area of coil

Better to send milli-Volt over 10 m cable than a micro-VoltBetter to integrate a milli-Volt than a micro-Volt

Gain=100

Kirsten Hacker


10/14/04 18

Pre-amp DC drift contribution

LS480Integrator+

10 m cable +500 Ohmresistor

Integrator +10 m cable +Ectron 560Pre-amp+500 Ohmresistor

Scale corrected for gain

Tolerance=2e^-6 V*s

Kirsten Hacker


10/14/04 19

Progress

LabView FPGA triggering

Hall Probe comparisons

Ectron pre-amp + LS480 Fluxmeter

kirsten hacker triggering and measurement devices for lcls undulator…[email protected]...

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