Energy and Longitudinal Bunch Measurements at the ......VRFQ = 50 kVkV, Vrebuncher = 45 kVkV, An...
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ENERGY AND LONGITUDINAL BUNCH ENERGY AND LONGITUDINAL BUNCH MEASUREMENTS AT THE SPIRAL2 RFQ EXIT MEASUREMENTS AT THE SPIRAL2 RFQ EXIT C. Jamet #, W. Le Coz, G. Ledu, S. Loret, C. Potier de Courcy , GANIL, Caen, France email:[email protected] C. Jamet #, W. Le Coz, G. Ledu, S. Loret, C. Potier de Courcy , GANIL, Caen, France email:[email protected] A new step of the SPIRAL2 commissioning started in December 2015 with the acceleration of a In 2016, different ion beams are qualified by the diagnostic test bench. This paper describes the first proton beam at the RFQ exit. A test bench, with all the different diagnostics which will be results of the energy measurements done by a Time of Flight monitor and the longitudinal first proton beam at the RFQ exit. A test bench, with all the different diagnostics which will be used on the SPIRAL2 accelerator was installed directly after the first rebuncher of the MEBT line results of the energy measurements done by a Time of Flight monitor and the longitudinal measurements using a fast faraday cup used on the SPIRAL2 accelerator, was installed directly after the first rebuncher of the MEBT line in order to qualify beams but also to test and make reliable the diagnostic monitors measurements using a fast faraday cup. in order to qualify beams but also to test and make reliable the diagnostic monitors. INTRODUCTION LONGITUDINAL BUNCH MEASUREMENTS INTRODUCTION LONGITUDINAL BUNCH MEASUREMENTS The SPIRAL2 driver is designed to accelerate and deliver proton beams, deuteron and ion A Fast Faraday Cup (FFC) will be positioned at the end of the MEBT to visualize, characterize beams with q/A=1/3 to NFS (Neutron for Science) and S3 (Super Separator Spectrometer) the bunch lengths and will be used to tune the 3 rebunchers of the MEBT. beams with q/A 1/3 to NFS (Neutron for Science) and S3 (Super Separator Spectrometer) experimental rooms B F t experimental rooms. Beam Features Th diff t b f t fl f th FFC i th f ll i t bl Currently, an Intermediate Test Bench is installed in the MEBT line. The commissioning is in The different beam features useful for the FFC are in the following table : progress in the accelerator part composed by 2 sources (a proton/deuteron source and an ion Features Values progress in the accelerator part composed by 2 sources (a proton/deuteron source and an ion source with a q/A=1/3) the LEBT lines a chopper a RFQ a rebuncher Features Values Maximum Intensity (mA) 5 source with a q/A 1/3), the LEBT lines, a chopper, a RFQ, a rebuncher . Maximum Intensity (mA) 5 Maximum power (deuterons) (kW) 75 Maximum power (deuterons) (kW) 7,5 σφ rms min 7° σφ rms min 7 σt rms min 220 ps σt rms min 220 ps Diagnostic description The FFC is a coaxial Faraday Cup with a water-cooled on the outer conductor . The inner A first proton beam was accelerated through the RFQ in December 2015. The FFC is a coaxial Faraday Cup with a water cooled on the outer conductor . The inner conductor (central part) is cooled by conduction via tree ceramic rods A polarized grid is used to In the first semester of 2016, the commissioning was done with proton conductor (central part) is cooled by conduction via tree ceramic rods. A polarized grid is used to shield the cup against the bunch advanced field and to suppress the secondary electrons effects In the first semester of 2016, the commissioning was done with proton and helium beams in pulse and CW mode shield the cup against the bunch advanced field and to suppress the secondary electrons effects. and helium beams in pulse and CW mode. The central part diameter is 45 mm. Thermal calculations give the following limits: Thermal calculations give the following limits: The central part limitation: INTERMEDIATE TEST BENCH The central part limitation: • 400 W in continuous beam INTERMEDIATE TEST BENCH • 400 W in continuous beam • 10ms/200ms with a pulse power of 7 5 kW The “Intermediate Test Bench” or “Diagnostic Plate” was built to test all the different diagnostics: • 10ms/200ms with a pulse power of 7.5 kW Th id li it ti The grid limitation: 1 /200 ith l f 7 5 kW It it ith ACCT DCCT d FC • 1ms/200ms with a pulse power of 7.5 kW • Intensity with ACCT, DCCT and FC T P fil • Transverse Profiles FFC bandwidth • Transverse emittance FFC bandwidth The FFC bandwidth is measured with a • Phases and Energy with the Time of Flight The FFC bandwidth is measured with a Vector Network Analyzer Agilent 8753 ES by (TOF) monitor Vector Network Analyzer, Agilent 8753 ES by reflection • Longitudinal profile with a Fast Faraday Cup reflection. Th FFC b d idth t 10 dB i 2 GH Longitudinal profile with a Fast Faraday Cup (FFC) and a Beam Extension Monitor (BEM) The FFC bandwidth at -10 dBm is 2 GHz. (FFC) and a Beam Extension Monitor (BEM) • Beam Position Phase and Ellipticity with 2 Acquisition system • Beam Position, Phase and Ellipticity with 2 Beam Position Monitors (BPM) Acquisition system An oscilloscope Agilent DSO9404A with 4 Beam Position Monitors (BPM) An oscilloscope Agilent DSO9404A with 4 analog channels and bandwidths of 4GHz analog channels and bandwidths of 4GHz di it li th l FFC i l Thi digitalizes the pulse FFC signal. This BEAM ENERGY PRINCIPLE oscilloscope was chosen also for these EPICS BEAM ENERGY PRINCIPLE drivers. The beam energy is measured by using 3 electrodes pick up The energy is calculated by a Time The beam energy is measured by using 3 electrodes pick-up. The energy is calculated, by a Time of flight method from the electrode phases and the distances between each electrode of flight method, from the electrode phases and the distances between each electrode. A d di td l t i b I/Q d d l ti th d th I h t I(t) Proton bunch measurements A dedicated electronic measures, by an I/Q demodulation method, the In-phase component I(t) Proton bunch measurements VRFQ = 50 kV Vrebuncher = 45 kV and the Quadrature component Q(t) of the first harmonic. VRFQ = 50 kV, Vrebuncher = 45 kV, I beam 4 mA An EPICS Interface, connected to the TOF electronic device by a Modbus-TCP link , calculates I beam = 4 mA the phases and the amplitudes from these components following by the energy calculation. BEAM ENERGY MEASUREMENTS Beam and TOF Features Features Values Beam and TOF Features Th b f t th f ll i Frequency (MHz) 88.052 The beam features were the following : P t It it f f 10 At 5 A 5 • Proton Intensity: from few 10μA to 5mA 5 Period (ns) 11 36 • Helium 4 He 2+ Intensity: few 10 μA to 1 mA Period (ns) 11.36 Energy E (MeV/A) 0 75 • Slow Chopper duty cycle: From 1/10000 to 1/1 Energy E (MeV/A) 0.75 Velocity β=v/c 0 04 • Chopper Frequency: 1Hz to 5 Hz Velocity β=v/c 0.04 L th bt 2 b h L ( ) 13 6 Length between 2 bunches Lacc (cm) 13.6 L th bt TOF1 TOF2 ( ) 1 616 FWHM: 800 ps σt calculated from the pulse = 328 ps σt simulated with tracewin = 220 ps Length between TOF1-TOF2 (m) 1.616 FWHM: 800 ps, σt calculated from the pulse 328 ps, σt simulated with tracewin 220 ps Length between TOF2-TOF (cm) 13 The spectral density is determined from the pulse signal by a matlab program Bunch number between TOF1-TOF3 12 The spectral density is determined from the pulse signal by a matlab program. Electrode diameter (mm) 80 Helium bunch measurements Helium bunch measurements VRFQ 80 kV I b 1 1 A Proton energy measurements VRFQ = 80 kV, I beam = 1,1 mA Th b h l th i ti i d t 75 kV d th l ti l t thi lt The beam energy is firstly measured with the RFQ “on” and the rebuncher “off” with different The bunch length is optimized at 75 kV and the pulse time values at this voltage are: beam intensities. VRFQ = 50 kV, I beam crest = 3.9 mA FWHM: 1,05 ns, σt calculated from the pulse = 443 ps, σt simulated with tracewin = 280 ps BEM and FFC comparison The table “Valeurs” in the page “Mesures” of the graphical Interface indicates: BEM and FFC comparison A Bunch Extension Monitor (BEM) is installed at the same location than the FFC on the Test A Bunch Extension Monitor (BEM) is installed at the same location than the FFC on the Test Bench (see poster TUPG59) Bench. (see poster TUPG59) • The X and Y signal components The X and Y signal components • The calculated modules and phases The BEM amplitude is normalised to have the same The calculated modules and phases • The bunch number The BEM amplitude is normalised to have the same pulse area than the FFC one • The bunch number pulse area than the FFC one. I th “E i ” f The FFC pulse shape is larger than the BEM pulse In the “Energie” frame Th b TOF1 d TOF3 The FFC pulse shape is larger than the BEM pulse. • The energy between TOF1 and TOF3 • The energy standard deviation At 75kV the rebuncher phase is shifted on 360° the pulse width is calculated in function of this At 75kV, the rebuncher phase is shifted on 360 , the pulse width is calculated in function of this phase phase . Helium energy measurements Rebuncher on Helium energy measurements VRFQ = 80 kV I crest = 1 1 mA Energy (keV) Rebuncher off Rebuncher on V = 75 kV, φ = -67,9° VRFQ = 80 kV, I crest = 1.1 mA, The energy is also calculated between each V 75 kV, φ 67,9 E 12 (TOF1-TOF2) 727.95 727.28 The energy is also calculated between each electrode The 3 values are very similar E 12 (TOF1 TOF2) 727.95 727.28 E 13 (TOF1-TOF3) 727.96 727.28 electrode. The 3 values are very similar . E 23 (TOF2-TOF3) 728.07 727.30 The FFC curve shows a limitation in time The FFC curve shows a limitation in time. The minimum value of σt is equal to 440 ps Optimization and improvements The minimum value of σt is equal to 440 ps. When the rebuncher is started and when its phase is shifted, the beam is accelerated or I i th BEM ti d t 244 ith t i i ltd t 280 decelerated in function of the phase. The bunch numbers between TOF1/TOF2 and TOF1/TOF3 In comparison, the BEM time go down to 244 ps with a tracewin simulated σt = 280 ps. F ll i th t th l l t d t th FFC li it d b d idth d change. The solution consists to choose E12 or E13 in function of N12 and N13. The bunch Following these measurements, the pulse enlargement due to the FFC limited bandwidth and change. The solution consists to choose E12 or E13 in function of N12 and N13. The bunch number that is farthest from the value change is chosen with its corresponding energy cable distortion is estimated between 120 to 160 ps. number that is farthest from the value change is chosen with its corresponding energy . CONCLUSION CONCLUSION The SPIRAL2 RFQ injector commissioning is started since the beginning of 2016 with proton and helium beams It will soon continue with heavier ion beams The SPIRAL2 RFQ injector commissioning is started since the beginning of 2016 with proton and helium beams. It will soon continue with heavier ion beams. As shown the results of the energy and bunch length monitors are encouraging Their functioning responds to the needs and wi ll allow the characterization of the various injector beams As shown, the results of the energy and bunch length monitors are encouraging. Their functioning responds to the needs and will allow the characterization of the various injector beams. F th TOF it t di ill b d t i l lit d ith i l ti t th ti i l/ i i f ti f th b it it d t th t ith th For the TOF monitor, studies will be done to compare signal amplitude with simulations, to measure the ratio signal/noise in function of the beam intensity and to compare the measurements with the l ltd calculated accuracy . A signal processing of the Fast Faraday Cup should minimize the signal enlargement caused by the limited bandwidth of the Faraday cup.
Transcript of Energy and Longitudinal Bunch Measurements at the ......VRFQ = 50 kVkV, Vrebuncher = 45 kVkV, An...
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ENERGY AND LONGITUDINAL BUNCHENERGY AND LONGITUDINAL BUNCH MEASUREMENTS AT THE SPIRAL2 RFQ EXITMEASUREMENTS AT THE SPIRAL2 RFQ EXIT
C. Jamet #, W. Le Coz, G. Ledu, S. Loret, C. Potier de Courcy, GANIL, Caen, France email:[email protected]. Jamet #, W. Le Coz, G. Ledu, S. Loret, C. Potier de Courcy, GANIL, Caen, France email:[email protected]
A new step of the SPIRAL2 commissioning started in December 2015 with the acceleration of a In 2016, different ion beams are qualified by the diagnostic test bench. This paper describes thep gfirst proton beam at the RFQ exit. A test bench, with all the different diagnostics which will be
, q y g p presults of the energy measurements done by a Time of Flight monitor and the longitudinalfirst proton beam at the RFQ exit. A test bench, with all the different diagnostics which will be
used on the SPIRAL2 accelerator was installed directly after the first rebuncher of the MEBT lineresults of the energy measurements done by a Time of Flight monitor and the longitudinalmeasurements using a fast faraday cupused on the SPIRAL2 accelerator, was installed directly after the first rebuncher of the MEBT line
in order to qualify beams but also to test and make reliable the diagnostic monitorsmeasurements using a fast faraday cup.
in order to qualify beams but also to test and make reliable the diagnostic monitors.
INTRODUCTION LONGITUDINAL BUNCH MEASUREMENTSINTRODUCTION LONGITUDINAL BUNCH MEASUREMENTSThe SPIRAL2 driver is designed to accelerate and deliver proton beams, deuteron and ion A Fast Faraday Cup (FFC) will be positioned at the end of the MEBT to visualize, characterize g p ,beams with q/A=1/3 to NFS (Neutron for Science) and S3 (Super Separator Spectrometer)
y p ( ) p ,the bunch lengths and will be used to tune the 3 rebunchers of the MEBT. beams with q/A 1/3 to NFS (Neutron for Science) and S3 (Super Separator Spectrometer)
experimental roomse bu c e g s a d be used o u e e 3 ebu c e s o e
B F texperimental rooms. Beam FeaturesTh diff t b f t f l f th FFC i th f ll i t blCurrently, an Intermediate Test Bench is installed in the MEBT line. The commissioning is in The different beam features useful for the FFC are in the following table :y, g
progress in the accelerator part composed by 2 sources (a proton/deuteron source and an ion Features Valuesprogress in the accelerator part composed by 2 sources (a proton/deuteron source and an ionsource with a q/A=1/3) the LEBT lines a chopper a RFQ a rebuncher
Features ValuesMaximum Intensity (mA) 5source with a q/A 1/3), the LEBT lines, a chopper, a RFQ, a rebuncher. Maximum Intensity (mA) 5Maximum power (deuterons) (kW) 7 5Maximum power (deuterons) (kW) 7,5σφ rms min 7°σφ rms min 7σt rms min 220 psσt rms min 220 ps
Diagnostic descriptiong pThe FFC is a coaxial Faraday Cup with a water-cooled on the outer conductor. The inner
A first proton beam was accelerated through the RFQ in December 2015.The FFC is a coaxial Faraday Cup with a water cooled on the outer conductor. The innerconductor (central part) is cooled by conduction via tree ceramic rods A polarized grid is used top g
In the first semester of 2016, the commissioning was done with protonconductor (central part) is cooled by conduction via tree ceramic rods. A polarized grid is used toshield the cup against the bunch advanced field and to suppress the secondary electrons effectsIn the first semester of 2016, the commissioning was done with proton
and helium beams in pulse and CW modeshield the cup against the bunch advanced field and to suppress the secondary electrons effects.
and helium beams in pulse and CW mode.The central part diameter is 45 mm.pThermal calculations give the following limits:Thermal calculations give the following limits:The central part limitation:
INTERMEDIATE TEST BENCHThe central part limitation:• 400 W in continuous beamINTERMEDIATE TEST BENCH • 400 W in continuous beam• 10ms/200ms with a pulse power of 7 5 kWThe “Intermediate Test Bench” or “Diagnostic Plate” was built to test all the different diagnostics: • 10ms/200ms with a pulse power of 7.5 kWTh id li it tiThe grid limitation:
1 /200 ith l f 7 5 kWI t it ith ACCT DCCT d FC
• 1ms/200ms with a pulse power of 7.5 kW• Intensity with ACCT, DCCT and FC
T P fil• Transverse Profiles FFC bandwidth• Transverse emittance FFC bandwidthThe FFC bandwidth is measured with a• Phases and Energy with the Time of Flight The FFC bandwidth is measured with aVector Network Analyzer Agilent 8753 ES bygy g(TOF) monitor Vector Network Analyzer, Agilent 8753 ES byreflection( )• Longitudinal profile with a Fast Faraday Cup reflection.Th FFC b d idth t 10 dB i 2 GHLongitudinal profile with a Fast Faraday Cup(FFC) and a Beam Extension Monitor (BEM) The FFC bandwidth at -10 dBm is 2 GHz.(FFC) and a Beam Extension Monitor (BEM)• Beam Position Phase and Ellipticity with 2 Acquisition system• Beam Position, Phase and Ellipticity with 2
Beam Position Monitors (BPM)Acquisition systemAn oscilloscope Agilent DSO9404A with 4Beam Position Monitors (BPM) An oscilloscope Agilent DSO9404A with 4analog channels and bandwidths of 4GHzanalog channels and bandwidths of 4GHzdi it li th l FFC i l Thidigitalizes the pulse FFC signal. This
BEAM ENERGY PRINCIPLEoscilloscope was chosen also for these EPICS
BEAM ENERGY PRINCIPLE drivers.The beam energy is measured by using 3 electrodes pick up The energy is calculated by a TimeThe beam energy is measured by using 3 electrodes pick-up. The energy is calculated, by a Timeof flight method from the electrode phases and the distances between each electrodeof flight method, from the electrode phases and the distances between each electrode.A d di t d l t i b I/Q d d l ti th d th I h t I(t) Proton bunch measurementsA dedicated electronic measures, by an I/Q demodulation method, the In-phase component I(t) Proton bunch measurements
VRFQ = 50 kV Vrebuncher = 45 kVand the Quadrature component Q(t) of the first harmonic. VRFQ = 50 kV, Vrebuncher = 45 kV,I beam 4 mAAn EPICS Interface, connected to the TOF electronic device by a Modbus-TCP link , calculates I beam = 4 mAy
the phases and the amplitudes from these components following by the energy calculation.p p p g y gy
BEAM ENERGY MEASUREMENTS
Beam and TOF Features Features ValuesBeam and TOF FeaturesTh b f t th f ll i Frequency (MHz) 88.052The beam features were the following :
P t I t it f f 10 A t 5 A
q y ( )5• Proton Intensity: from few 10µA to 5mA 5Period (ns) 11 36• Helium 4He 2+ Intensity: few 10 µA to 1 mA Period (ns) 11.36Energy E (MeV/A) 0 75• Slow Chopper duty cycle: From 1/10000 to 1/1 Energy E (MeV/A) 0.75Velocity β=v/c 0 04pp y y• Chopper Frequency: 1Hz to 5 Hz Velocity β=v/c 0.04L th b t 2 b h L ( ) 13 6pp q y Length between 2 bunches Lacc (cm) 13.6
L th b t TOF1 TOF2 ( ) 1 616 FWHM: 800 ps σt calculated from the pulse = 328 ps σt simulated with tracewin = 220 psLength between TOF1-TOF2 (m) 1.616 FWHM: 800 ps, σt calculated from the pulse 328 ps, σt simulated with tracewin 220 ps
Length between TOF2-TOF (cm) 13 The spectral density is determined from the pulse signal by a matlab programBunch number between TOF1-TOF3 12 The spectral density is determined from the pulse signal by a matlab program.
Electrode diameter (mm) 80 Helium bunch measurements( ) Helium bunch measurementsVRFQ 80 kV I b 1 1 AProton energy measurements VRFQ = 80 kV, I beam = 1,1 mATh b h l th i ti i d t 75 kV d th l ti l t thi ltThe beam energy is firstly measured with the RFQ “on” and the rebuncher “off” with different The bunch length is optimized at 75 kV and the pulse time values at this voltage are:
beam intensities. VRFQ = 50 kV, I beam crest = 3.9 mA FWHM: 1,05 ns, σt calculated from the pulse = 443 ps, σt simulated with tracewin = 280 ps,
BEM and FFC comparisonThe table “Valeurs” in the page “Mesures” of the graphical Interface indicates: BEM and FFC comparisonA Bunch Extension Monitor (BEM) is installed at the same location than the FFC on the Test
p g g pA Bunch Extension Monitor (BEM) is installed at the same location than the FFC on the TestBench (see poster TUPG59)Bench. (see poster TUPG59)
• The X and Y signal componentsThe X and Y signal components• The calculated modules and phases The BEM amplitude is normalised to have the sameThe calculated modules and phases• The bunch number
The BEM amplitude is normalised to have the samepulse area than the FFC one• The bunch number pulse area than the FFC one.
I th “E i ” f The FFC pulse shape is larger than the BEM pulseIn the “Energie” frameTh b TOF1 d TOF3
The FFC pulse shape is larger than the BEM pulse.• The energy between TOF1 and TOF3• The energy standard deviation
At 75kV the rebuncher phase is shifted on 360° the pulse width is calculated in function of thisAt 75kV, the rebuncher phase is shifted on 360 , the pulse width is calculated in function of thisphasephase .
Helium energy measurements Rebuncher onHelium energy measurementsVRFQ = 80 kV I crest = 1 1 mA Energy (keV) Rebuncher off
Rebuncher onV = 75 kV, φ = -67,9°VRFQ = 80 kV, I crest = 1.1 mA,
The energy is also calculated between eachV 75 kV, φ 67,9
E 12 (TOF1-TOF2) 727.95 727.28The energy is also calculated between eachelectrode The 3 values are very similar
E 12 (TOF1 TOF2) 727.95 727.28E 13 (TOF1-TOF3) 727.96 727.28electrode. The 3 values are very similar. ( )E 23 (TOF2-TOF3) 728.07 727.30 The FFC curve shows a limitation in time( ) The FFC curve shows a limitation in time.
The minimum value of σt is equal to 440 psOptimization and improvements The minimum value of σt is equal to 440 ps.When the rebuncher is started and when its phase is shifted, the beam is accelerated or
I i th BEM ti d t 244 ith t i i l t d t 280p
decelerated in function of the phase. The bunch numbers between TOF1/TOF2 and TOF1/TOF3 In comparison, the BEM time go down to 244 ps with a tracewin simulated σt = 280 ps.F ll i th t th l l t d t th FFC li it d b d idth d
pchange. The solution consists to choose E12 or E13 in function of N12 and N13. The bunch Following these measurements, the pulse enlargement due to the FFC limited bandwidth andchange. The solution consists to choose E12 or E13 in function of N12 and N13. The bunchnumber that is farthest from the value change is chosen with its corresponding energy cable distortion is estimated between 120 to 160 ps.number that is farthest from the value change is chosen with its corresponding energy.
CONCLUSIONCONCLUSIONThe SPIRAL2 RFQ injector commissioning is started since the beginning of 2016 with proton and helium beams It will soon continue with heavier ion beamsThe SPIRAL2 RFQ injector commissioning is started since the beginning of 2016 with proton and helium beams. It will soon continue with heavier ion beams.As shown the results of the energy and bunch length monitors are encouraging Their functioning responds to the needs and will allow the characterization of the various injector beamsAs shown, the results of the energy and bunch length monitors are encouraging. Their functioning responds to the needs and will allow the characterization of the various injector beams.F th TOF it t di ill b d t i l lit d ith i l ti t th ti i l/ i i f ti f th b i t it d t th t ith thFor the TOF monitor, studies will be done to compare signal amplitude with simulations, to measure the ratio signal/noise in function of the beam intensity and to compare the measurements with the
l l t dcalculated accuracy.A signal processing of the Fast Faraday Cup should minimize the signal enlargement caused by the limited bandwidth of the Faraday cup.
