Slide 1

2003 MSE Calibration: Preliminary Analysis

H. Yuh, S. D. Scott, R. Grantez

27 May 2003

Note: This presentation is best viewed with PowerPoint 2002 or later

File: 27may2003 MSE calibration.ppt

Slide 2

Shot Summary 21-May-2003: A Good Day

• 35 shots total

– 3 - Lost due to DNB gate-valve permissive (90 minutes)– 1 - No-power test– 1 - No-field fault– 2 - Short DNB, too short to use

• 28 usable MSE shots

– 3 shots with about 25 ms DNB duration – usable– 5 shots with ~5 ms faults (45 ms good DNB) – good– 20 shots with full-length, 50-ms DNB

Slide 3

Calibration Data Obtained

• EF3 and EF4 scan at both TF=2.7 and TF=5.4

• One shot at TF = 4.5 Tesla

• One shot each with EF1 and EF2

• Several shots at same conditions to determine shot-to-shot reproducibility.

Slide 4

Two Analysis Methods Agree Well

Channels 0-8:Average Difference = -0.003 degreesScatter = 0.05 degrees

Channel 9 (innermost):Average Difference = 0.06 degreesScatter = 0.14 degrees

Slide 5

Statistical Uncertainty is ~0.06 Degrees

• Inferred from standard deviation in mean angle (10 x 5-ms intervals)• Scatter is larger for innermost channel• In frame of polarimeter. • Shot-shot scatter is somewhat larger – being investigated.

Slide 6

MSE Measured Angles at BT=5.4 Tesla

Slide 7

MSE Measured Angles at BT=5.4 Tesla

Slide 8

Overall Trends Look Very Consistent – No Special Behavior at EF=0

Slide 9

Shots with Matched Ratio of TF/EF

Slide 10

Calibration Against Expected Angles

• Compute field-line pitch-angle with mflux for all shots.

• Data looks quite good – consitent trends -- except for outer three channels with EF3=EF4=0.

• Faraday rotation effect appears to be small.

• Analysis in progress.

Slide 11

MSE Measured Angles at BT=2.7 Tesla

Slide 12

We expect small variation in measured angles at the outer channels due to viewing geometry

Actual field-line angle (degrees)

Mse

mea

sure

d a

ngl

e (d

egre

es)

Slide 13

The expected nonlinearity is small

Slide 14

A Puzzle: Profiles of Measured Angles for EF=0

‘Uptick’ at edge not understood

Rmajor (cm)

Slide 15

Angle in Edge Channels

Measured Angle in Channel 4

Mea

sure

d A

ngle

in O

ther

Cha

nne

ls

Edge channel

Core channels

Slide 16

Shot-Shot Scatter Sometimes Consistent with Measured Variation within a Single Shot

Slide 17

Shot-Shot Scatter Sometimes Consistent with Measured Variation within a Single Shot

Slide 18

Shot-Shot Scatter Sometimes Not Consistent with Measured Variation within a Single Shot

Note: these shots have TF = 5.4 Tesla and EF3 = EF4 = 0, which seem to be problematic in other ways.

Slide 19

MFLUX Pitch-Angles during EF scan at 5.4 Tesla

Slide 20

MFLUX Mapped Pitch-Angles during EF scan at 5.4 Tesla

Slide 21

Measured MSE Angles during EF scan at 5.4 Tesla

Strong rise in measuredangle at outer edge

Strong rise in measuredangle at innermost point.

Slide 22

MFLUX Pitch-Angles during EF scans at 2.7 Tesla

Slide 23

MFLUX Mapped Pitch-Angles during EF scan at 2.7 Tesla

Slide 24

Measured MSE Angles during EF scans at 2.7 Tesla

Reasonably well-behaved on innermost points.

Behavior at edgesimilar to thatat 5.4 Tesla

Slide 25

Measured MSE Polarization Fraction

Polarization fraction =

F

Imax - Imin

F (Imax + Imin)

Typical range of measured angles

Slide 26

Polarization Fraction during 5.4 Tesla EF Scan

+/- 0.05

• Systematic +/- 0.05 shot-to-shot variation.

• Polarization fraction is much smaller on innermost channel.

Slide 27

Polarization Fraction during 2.7 Tesla EF Scan

• Values at outer edge reduced from (0.6-0.7) in 5.4 Tesla scan to (0.5-0.6) in 2.7 Tesla scan.• Innermost channel not different from others.

+/- 0.05

Slide 28

Polarization During EF4 Scan at 5.4 Tesla

• Polarization fraction generally increases with increasing EF4.

• Suggests possible tuning problems but effect on measured angle should (??) be small.

Slide 29

Polarization During EF3 Scan at 5.4 Tesla

Some trend toward increasing polarization fraction with increasing EF4

Slide 30

Polarization During EF3+4 Scan at 5.4 Tesla

Scaling with EF is not so clear in this dataset.

Slide 31

Polarization During EF4 Scan at 2.7 Tesla

Scaling with EF is not so clear in this dataset.

Slide 32

Polarization During EF3 Scan at 2.7 Tesla

No clear scaling with EF in this dataset.

Slide 33

Phase Offset between 40 kHz PEM drive and Signal

• Varies about mean value by +/- 0.05 radians.

• No apparent trend with EF or TF

Offs

et b

etw

een

PE

M d

rive

and

MS

E S

igna

l (ra

dian

s)

Slide 34

Phase Offset between 44 kHz PEM drive and Signal

• Varies about mean value by +/- 0.10 radians.

• No apparent trend with EF or TF

Offs

et b

etw

een

PE

M d

rive

and

MS

E S

igna

l (ra

dian

s)

Slide 35

Effect of Phase Shift on Measured MSE Angle

Phase Offset Amplitude Ratio Angle (radians) (degrees)

- 0.125 0.9919 0.120 - 0.100 0.9948 0.075 - 0.075 0.9970 0.043 - 0.050 0.9986 0.020 - 0.025 0.9996 0.006 0.000 1.0000 0.000 0.025 0.9997 0.004 0.050 0.9989 0.016 0.075 0.9974 0.037 0.100 0.9952 0.069 0.125 0.9925 0.108

Angle = 0.5 * atan(Amplitude Ratio)

Conclusion: the observed variability in phase shift might account for0.02 – 0.08 degrees shot-to-shot variability.

Slide 36

Conclusions

• Tuning is definitely off for innermost channel at 5.4 Tesla.

• Polarization fraction measurements might suggest tuning problems generally, but hard to see how this could appreciably affect our measurements.

• Variability in phase shift between PEM and MSE signals is reasonably small … not enough to account for unusual behavior of edge channels during calibration.