Improved Noise Suppression for MSE Analysis20 KHz PEM: Nearly equal Up and Down pointsPEM #5: more ‘down’ than ‘up’ pointsExample of PEM Drive with 5-volt valuesPhase of Signal: 40 kHz ComponentSlide 6Phase of Signal: 44 kHz ComponentSlide 8Phase of noise: 40 kHz ComponentSlide 10Phase of noise: 44 kHz ComponentSlide 12Noise at 40 kHz versus timeNoise at 44 kHz versus timeNoise at 40 kHz: profiles vs channel numberNoise at 44 kHz: profiles vs channel numberPresent MSE Analysis TechniqueNew MSE Analysis TechniqueNew Analysis: doesn’t affect calibration muchNew Analysis: less scatter in calibration dataOld Analysis: Possible problems with q-measurement at high density? – individual shotsNew Analysis: Little Dependence of MSE Angle on DensityShot-to-Shot Scatter in MSE angle is ‘generally’ reduced with new analysis technique – but not always.SET N: ò nedl (ch4) = 0.65 ´1020 m-2 nebar = 0.90 ´1020 m-3SET G: NeL4 = 0.92e20 nebar = 1.29 ´1020 m-3SET D: NeL4 = 1.00e20 nebar = 1.39 ´1020 m-3SET E2: NeL4 = 1.15e20 nebar = 1.59 ´1020 m-3Scatter in Real Pitch-Angle DegreesConclusionsRatio of signal levels: R=85.5 / R=84.0MSE channels closer to plasma coreExtract data from shot 010Data – shot 011 onlyData – shot 021Data – shot 023Extreme comparison: shot 10 vs 21Five consecutive shots – varying densitySame data – log scaleOld Analysis: possible problems with q-measurement at high density?Improved Noise Suppression for MSE AnalysisDNB Group discussionNovember 25, 2002New material 27 Dec 2002S. D. ScottPPPLThanks to Gerrit Kramer and Fred Levinton, PPPLUpdate MSE Data Analysis 27 Dec 2002.ppt20 KHz PEM: Nearly equal Up and Down points23 points ‘up’22 points ‘down’Update MSE Data Analysis 27 Dec 2002.pptPEM #5: more ‘down’ than ‘up’ points22 points ‘up’27 points ‘down’Update MSE Data Analysis 27 Dec 2002.pptExample of PEM Drive with 5-volt valuesShot 1021108007Time index Both PEM drives are affected. Typically, about 50 data points are affected per-shot out of 130,000 = 0.05%. Not a big deal … unless it gets worse.Affected pointsUpdate MSE Data Analysis 27 Dec 2002.pptPhase of Signal: 40 kHz Component Shot: 10210230181st DNB blip2nd DNB blipPhase constant with radius, except for ~180-degree shift at innermost pointEDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptPhase of Signal: 40 kHz Component Shot: 10210230181st DNB blip2nd DNB blipPhase constant with radius, except for ~180-degree shift at innermost point = 180o = 180oEDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptPhase of Signal: 44 kHz ComponentShot: 10210230181st DNB blip2nd DNB blipPhase constant with radius, except for 180-degree shift at innermost pointEDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptPhase of Signal: 44 kHz ComponentShot: 10210230181st DNB blip2nd DNB blip = 180oPhase constant with radius, except for 180-degree shift at innermost pointEDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptPhase of noise: 40 kHz ComponentShot: 1021023018Time bin #1#2#3#4#5#6EDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptPhase of noise: 40 kHz ComponentShot: 1021023018Time bin #1#2#3#4#5#6Phase reasonably constant in radius: within a 20-degree bandnear the edge, somewhat larger at the core = 180o20-degree bandsEDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptPhase of noise: 44 kHz ComponentTime bin #1#2#3#4#5#6EDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptPhase of noise: 44 kHz ComponentTime bin #1#2#3#4#5#6Phase constant in edge, but varies considerably near the core20-degree bandsEDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptNoise at 40 kHz versus timeTime index (6 = before DNB, 7 = after DNB)0 (edge)123456789 (core)InterpolationFor DNBUpdate MSE Data Analysis 27 Dec 2002.pptNoise at 44 kHz versus timeTime index (6 = before DNB, 7 = after DNB)0 (edge)123456789 (core)InterpolationFor DNBNote factor ~10 increase betweenpoints that are used to provideInterpolationUpdate MSE Data Analysis 27 Dec 2002.pptNoise at 40 kHz: profiles vs channel numberJust before DNBLast noise time pointEDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptNoise at 44 kHz: profiles vs channel numberJust before DNBLast noise time pointEDGE MSE CHANNEL COREUpdate MSE Data Analysis 27 Dec 2002.pptPresent MSE Analysis Technique• Current method: Perform FFT on MSE signal for each channel, then fit a gaussian to the FFT amplitudes near 40 and 44 KHz, then compute the area under the gaussian to obtain the amplitude at these frequencies. To account for noise, subtract the no-beam fft amplitudes on a frequency- by-frequency basis before fitting a gaussian to the net signal.• Limitation of current method: doesn’t impose any requirement that the measured signals be synchronous with the phase of the PEM.• Particularly in situations with weak polarization fraction and large noise, this could lead to over-counting the noise photons. • Also, the current method requires that the time periods for the beam and no-beam signal acquisition be identical – otherwise the beam and no-beam FFT arrays will be on a different frequency grid.Update MSE Data Analysis 27 Dec 2002.pptNew MSE Analysis Technique• New method: construct a sine wave that is synchronous with the PEM square-wave drives.• We observed that the MSE signals were consistently about 0.25 and 0.05 radians ‘behind’ the PEM square-wave drives on both calibration shots and plasma shots having high signal-to-noise. • So what we really do is construct sine waves that are about 0.25 and 0.50 radians lagging the PEM drive.• Multiply each MSE signal by the sine wave.• Compute the FFT of the product, and take the lowest-frequency component. This component is the 40 or 44 khz amplitude.• Calculate the angle from atan (40-khz amplitude / 44-khz amplitude) in the usual way.• Advantage: eliminate signals that are not in phase with the PEMs.Update MSE Data Analysis 27 Dec 2002.pptNew Analysis: doesn’t affect calibration muchUpdate MSE Data Analysis 27 Dec 2002.pptNew Analysis: less scatter in calibration dataScatter taken from dividing beam pulse into three parts (shot 1021004011 – I