David MacNair

Region 29 Quad 501 Test macnair@slac.stanford.edu

7/6/06

Region 29 Quad 501 Test

Purpose: Characterize RMS noise on Linac Quads in the 0.1 Hz to 10 Hz region

LCLS PRD specifies less then 0.05% RMS stability over 10 seconds

Linac Quad power supplies are 20+ years old

Bulk supply is SCR controlled using a SLAC transductor for current regulation

Boost supply uses an internal shunt for current regulation

The RMS noise in the 0.1Hz to 10Hz region has never been measured

David MacNair

Region 29 Quad 501 Test macnair@slac.stanford.edu

7/6/06

Region 29 Quad Configuration

Each region has 8 Quad magnets connected in series

Each string has a 200 amp SCR bulk supply

Each magnet has a 20 amp boost supply

Need to measure the current in the bulk and boost power supplies simultaneously to determine actual magnet current

David MacNair

Region 29 Quad 501 Test macnair@slac.stanford.edu

7/6/06

Test Setup

Zero Flux transductors to read bulk and boost current

Two HP3458A meters to read the two transductors simultaneously 60 times per second for 30 seconds

Laptop computer to save data (1800 samples per transductor)

Laptop computer running a SCP to control power supply current

HSTA bit 0x4000 needed to be cleared to allow independent setting of supplies

David MacNair

Region 29 Quad 501 Test macnair@slac.stanford.edu

7/6/06

Test Performed

Set the boost supply to 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 17.5 and 20.0 amps (8 setpoints)

Set the bulk supply to 0, 5, 10, 15, 20, 25, 30, 35, 40 , and 45 amps (10 setpoints)

Read 30 seconds of data at the 80 different combinations

Used Excel to combine bulk and boost currents, subtract 30 second average, and calculate absolute RMS noise

Absolute RMS noise divided by average current and plotted as relative RMS noise

David MacNair

Region 29 Quad 501 Test macnair@slac.stanford.edu

7/6/06

POWER SUPPLY CURRENT REGION 29 QUAD 501 (BULK = 5A, BOOST = 5A)

-0.0200

-0.0150

-0.0100

-0.0050

0.0000

0.0050

0.0100

0.0150

1 61 121 181 241 301 361 421 481 541 601

SAMPLES (60 SAMPLES = 1 SECOND)

CU

RR

EN

T -

AV

G (

AM

PS

)

Bulk

Boost

David MacNair

Region 29 Quad 501 Test macnair@slac.stanford.edu

7/6/06

Region 29 Quad 501 RMS Noise (%) vs Current

0.0000

0.0100

0.0200

0.0300

0.0400

0.0500

0.0600

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0

Magnet Current (amps)

Pe

rce

nt

RM

S N

ois

e

0

5

10

15

20

25

30

35

40

45

David MacNair

Region 29 Quad 501 Test macnair@slac.stanford.edu

7/6/06

Summary

The current linac quad power supplies should be able to meet the 0.05% noise requirement

This is more then 100 times the typical noise (<0.0005%) on new installations using switchmode power supplies and zero flux transductors

Data files available @ U:\m\macnair\public\Reg29