FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of...

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FONT Hardware FONT Hardware Processing electronics and Processing electronics and current beam tests current beam tests Stephen Molloy Stephen Molloy Queen Mary, University of Queen Mary, University of London London

Transcript of FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of...

Page 1: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

FONT HardwareFONT Hardware

Processing electronics and Processing electronics and current beam testscurrent beam tests

Stephen MolloyStephen Molloy

Queen Mary, University of Queen Mary, University of LondonLondon

Page 2: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

FONTFONT• Fast feedback scheme to maintain Fast feedback scheme to maintain

luminosity at GLC/NLC.luminosity at GLC/NLC.• FONT 1FONT 1

– NLCTA, September 2002.NLCTA, September 2002.– ΔΔ//ΣΣ of pickoff signals mixed to baseband. of pickoff signals mixed to baseband.

• FONT 2FONT 2– NLCTA, January 2004.NLCTA, January 2004.– Log ratio of pickoff signals mixed to Log ratio of pickoff signals mixed to

baseband.baseband.

• FONT 3FONT 3– Currently conducting beam tests at ATF.Currently conducting beam tests at ATF.

Page 3: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

FONT 1FONT 1

• BPM with resonant BPM with resonant pickoffs.pickoffs.

• Used splitters and Used splitters and phase shifters to phase shifters to create create ΔΔ and and ΣΣ..

• 1/1/ΣΣ calculated digitally calculated digitally so this was from an so this was from an earlier pulse.earlier pulse.– First order correction to First order correction to

account for this.account for this.

Page 4: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

FONT 1 – Processing circuitFONT 1 – Processing circuit

Page 5: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

FONT 2 – First stage FONT 2 – First stage processingprocessing

• Same BPM hardware as FONT 1, but new Same BPM hardware as FONT 1, but new processing electronics.processing electronics.

• First stage of processing.First stage of processing.– Attenuate X-band signal to suitable level.Attenuate X-band signal to suitable level.– Mix to 400MHz.Mix to 400MHz.– Amplify to suitable level for second stage.Amplify to suitable level for second stage.

Page 6: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

FONT 2 – Second stageFONT 2 – Second stage• Synchronous demodulator mixes 400MHz to Synchronous demodulator mixes 400MHz to

baseband.baseband.

• Use log amplifiers to give:Use log amplifiers to give:– Log(top pickoff)Log(top pickoff)– Log(bottom pickoff)Log(bottom pickoff)

• The difference of these is the normalised position.The difference of these is the normalised position.

Page 7: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

Processor installed in tunnelProcessor installed in tunnel

Page 8: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

Monitor electronics outside Monitor electronics outside tunneltunnel

Page 9: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

ResolutionResolution

Resolution =~ 14μm

Page 10: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

ATF beam testsATF beam tests

• Two purposes of present beam tests:Two purposes of present beam tests:– Analysis of extraction line jitter.Analysis of extraction line jitter.– Tests of processing electronics for a Tests of processing electronics for a

future feedback experiment at ATF.future feedback experiment at ATF.

• Jitter measurement:Jitter measurement:– Jitter between trains.Jitter between trains.– Jitter within a train.Jitter within a train.

• Processing electronics:Processing electronics:– Two variations of a Two variations of a ΔΔ//ΣΣ scheme. scheme.

Page 11: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

Jitter monitorJitter monitor

Page 12: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

Jitter monitor - componentsJitter monitor - components

• Irregular coupler:Irregular coupler:– Striplines with coupling:Striplines with coupling:

• F(z)=0.5 [1+cos(2F(z)=0.5 [1+cos(2ππ(z/L))](z/L))]

– Delta function produces ~500MHz sine out.Delta function produces ~500MHz sine out.– Matches to 50Matches to 50ΩΩ impedance at a broad range of impedance at a broad range of

frequencies.frequencies.– Diode switch between outputs:Diode switch between outputs:

• Provides possibility of shorting outputs.Provides possibility of shorting outputs.

• Allows measurement of common mode rejection of Allows measurement of common mode rejection of hybrid.hybrid.

Page 13: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

Jitter monitor - componentsJitter monitor - components

• PIN diode controller:PIN diode controller:– Forward bias diode with 12V to close switch.Forward bias diode with 12V to close switch.– Reverse bias with -12V to open switch and Reverse bias with -12V to open switch and

insure low coupling between channels.insure low coupling between channels.– 12V is supplied to the diode via coupler output 12V is supplied to the diode via coupler output

lines.lines.

• 180° Hybrid:180° Hybrid:– Gives Gives ΔΔ and and ΣΣ of coupler output. of coupler output.

• Final amplifier to increase resolution.Final amplifier to increase resolution.

Page 14: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

Coupler output – first bunchCoupler output – first bunch

Page 15: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

Coupler output - multibunchCoupler output - multibunch

Page 16: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

Processing electronicsProcessing electronics

• Position output is mixed down Position output is mixed down ΔΔ..• Difference lies in LO source:Difference lies in LO source:

– Mix with 714MHz reference.Mix with 714MHz reference.• Requires stable reference phase.Requires stable reference phase.

– Mix with Mix with ΣΣ..• Requires flat charge profile over Requires flat charge profile over

train.train.

Page 17: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

714MHz reference stability714MHz reference stability

Page 18: FONT Hardware Processing electronics and current beam tests Stephen Molloy Queen Mary, University of London.

Next weekNext week• Further jitter measurementsFurther jitter measurements

– Calibration using upstream correctors.Calibration using upstream correctors.– Full multi-bunch measurement with ballistic Full multi-bunch measurement with ballistic

trajectory between the BPMs (ML8 and trajectory between the BPMs (ML8 and ML13).ML13).

• Stability of 714MHz reference is Stability of 714MHz reference is promisingpromising– Calibrate and measure resolution.Calibrate and measure resolution.– Latency is important for feedback experiment Latency is important for feedback experiment

and should be measured.and should be measured.

• Test “self-mixing” schemeTest “self-mixing” scheme– Simulations suggest this may be less Simulations suggest this may be less

sensitive to errors in cable lengths.sensitive to errors in cable lengths.