CERN’s Linac4 CesiatedSurface H Source IS03anibs2016.org/sites/nibs2016.org/files/MonO2.pdf ·...
Transcript of CERN’s Linac4 CesiatedSurface H Source IS03anibs2016.org/sites/nibs2016.org/files/MonO2.pdf ·...
CERN’s Linac4 Cesiated Surface H‐ Source • IS03a– Ion source operation during Linac4 commissioning
• IS03b– New beam optics, gather know how to improve transmission through the RFQ– emittances and profiles measurement results– D‐ beam test
• IS03c Hardware description • IS03‐p
– Proton beam optics– Very preliminary test results (intermediate optics)
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1. G. Voulgarakis, J. Lettry, B. Lefort and V. J. Correia Costa, Autopilot regulation for the Linac4 H- Ion source, NIBS-2016, Oxford.
2. S. Mattei, K. Nishida, M. Onai, J. Lettry, M. Q. Tran and A. Hatayama, Numerical simulation of the RF plasmadischarge in the Linac4 H- ion source, NIBS-2016, Oxford.
3. S. Abe, S. Nishioka, S. Mattei, A. Hatayama and J. Lettry, Effect of the Puller-electrode Voltage on the H- ExtractionMechanism in Linac4 Negative Ion Source, NIBS-2016, Oxford.
4. S. Briefi, S. Mattei, J. Lettry, and U. Fantz, Influence of the cusp field on the plasma parameters of the Linac4 H- ionsource, NIBS-2016, Oxford.
5. K. Nishida, M. Haase, M. Paoluzzi, A. Jones, A. Grudiev, S. Mattei, G. Voulgarakis, A. Butterworth, A. Hatayama and J.Lettry, Experimental investigation of the relation between plasma parameters and impedance in the Linac4 H- source,NIBS-2016, Oxford.
6. D. Rauner, S. Mattei, S. Briefi, U. Fantz, A. Hatayama, J. Lettry, K. Nishida and M.Q. Tran, Investigation of the RFEfficiency of Inductively Coupled Hydrogen Plasmas at 1MHz, NIBS-2016, Oxford.
Related plasma & H‐ source contributions:
CERN’s Linac4 Status
H‐ source
2017 2015 2014 2013
IS01Volume, DESY PG
IS02a,bCs‐surface
IS03aCs‐surf.
2018‐9 Connection to PSB
Reliability run
50 MeV p
160 MeV H‐
LEBT
Upgrade of the LHC injector chain:
From: 50 MeV p Linac2 To: 160 MeV H‐ Linac4& striping injectionInto the PS‐Booster
2
2016
HS‐test
50 MeV 105 MeV
IS03bCs‐surf.
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IS03a operation during L4 commissioning
Reliable during Linac4 50 MeV and 105 MeV Linac4 beam conditioning
Beams intensity 40‐50 mA Motorized Cs‐Valve
Autopilot: G. Voulgarakis Regulation of hydrogen and beam shape
based on H‐ pulse shape monthly cesiation ~ 5 mg restart of power converters
Intensity regulation: 35 to 45 mA Reduced HR operation load
To be improved: H‐ beam intensity Transmission through the LEBT drops
with increasing beam intensity Acceptance into RFQ below expectation
311/09/2016
Monthly Cesiation under Autopilot• LEBT VV closed (2 hours)• Reduced RF‐power: > 20 mA H‐ remaining Limit the peak of co‐
extracted electrons 5 mg delivered
Cs‐valve open
2.3
13
T‐Cs‐valve 200°
T‐Cs 120° e/H
‐30 mA
0
600
current [ m
A]
e‐dumpSourceEinzelH‐
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Transmission through the RFQ
Space charge compensation:• No additional gas injected• LEBT residual pressure: 1.2E‐6 mbar H2
H‐ beam LEBT BCT.1213
Transmission through the RFQ [80 %]
LEBT BCT.1213
RFQ BCT.3113
0
20
40
60
80
Tr_RFQ & H‐V SEM‐Grids to optimize source and LEBT settings: Source RF‐power and H2 injection Source, puller and Einzel Voltages LEBT: 2 solenoids, 4 steerers, LEBT SC gas injection RFQ RF‐power …
Onset of SC‐Compensation ~ 0.2 ms
IS03a settings: Sol_1,2: 101, 123 A, Source, Puller, Einzel:‐45, ‐36, 40 kV
0 0.2 0.3 0.40.1time [ms]
SCC
LEBT 32 mA
RFQ 26 mA
H‐current [ m
A], Tr. RFQ [%]
‐30 mA
511/09/2016
Key information delivered by the H‐ pulse shape
Low H2NominalHigh H2
RF‐ power
RF‐ phase
H‐curren
t
H2 starvation
0 mA
‐40 mA
SEJ SEJ + 600 s
Nom. pulse
oscillationPlasma meniscus –puller voltage
SCCSource HV oscillation
The pre‐chopper will hide some of these warnings 611/09/2016
Move of the linac4 LEBT’s Beam Current Transformer
H‐ beam dir.
Sol. 1 Sol. 2
VVBCT
Pre‐Chopper
FC
Grids
s2s1
The pre‐chopper removes head and tail and define the pulse length of the H‐ pulse as a function of the beam destination (i.e. ISOLDE, n‐ToF, experimental areas or LHC). LEBT modification driven by the need to dispose of the full H‐ pulse shape to maximize the effectiveness of the regulation algorithms implemented in Autopilot Side effect: The BCT now also sees the non‐
dumped co‐extracted electrons entering the LEBT711/09/2016
IS03a: operated in Linac4from Sep. 2015 to July 2016
1) Einzel lens2) Einzel lens support3) Ground electrode (center)4) Puller dump (12 g)5) Plasma Electrode
a) Plasma electrode (124 g)b) Armco shield (1 g)c) Support
6) Insulateur Al2O3
X‐Ray Fluorescence, Detection limit: (<0.05 g)
Total Cs injected: [~60, <200 mg]
1
2
3
45
6
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IS03 b,c layoutIS03bIS03c
Modification implemented:Operation: Quartz insulated Einzel lens HV
feedthrough Pulsed Einzel lens HV (up to 45 kV)
Beam optics studies driven: Angle of the plasma electrodes facing
the puller Increased filter field strength at
extraction (PE shield moved to puller) Angle of the puller electrode Aperture and size of the Co‐extracted
electron dumping Einzel lens geometry Entrance into the LEBT
Tests: RF 5‐turn solenoid antenna, shape and
range Floating plasma electrode Reduced plasma electrode aperture911/09/2016
Detail of the extraction optics
Plasma Generator
IS03a
IS03b,c
Armco Shield
Armco Shield
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IS03 b and c plasma generators
IS03b IS03c
• Plasma Electrode heater• Extraction hole diam. 6.5 mm• 5‐turn RF‐solenoid (identical to IS03a):
• Epoxy mould: 39 mm• Coil height: 26.5 mm• Dist. to PE‐hole: 31‐52 mm
• Floating Plasma Electrode ± 60 V• Extraction hole diam. 5.5 mm• 5‐turn RF‐solenoid:
• Epoxy mould: 48 mm• Coil height: 31 mm• Dist. to PE‐hole: 36‐72 mm 1111/09/2016
Linac4 Ion Source Test stand
Sol. 1
VV
BCT
Emittance meter
FCH‐VGrids
s1
SlitsH‐VGrids
LEBT‐pressure controlled Space charge compensation gas (H2, N2) Pre‐chopper : not implemented
L4 diagnosticsIdentical to Linac4
H2, N2
Profile meter U. Raich, F. Roncarolo
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IS03b IBSimu staged Emittance Simulation
Filter
0
20
40
0
‐20
‐40
50 100
norm, RMS = 0.34 ∙mm∙mradAt RFQ entrance (2.23 m)
Settings: 40 mA H‐, e/H = 3Source, puller, Einzel:‐45, ‐35.5, 35 kV Sol_1,2 = 97, 100 ALEBT SCC 4E‐6 mbar
(D. Fink)
Stages:1) Extraction and e‐dump2) Einzel lens3) LEBT (not shown)
1
2
[mm]
[mm]
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Emittance plot at RFQ entrance(D. Fink)
Settings: 40 mA H‐ e/H = 3Source puller Einzel:‐45, ‐35.5, 35 kV Sol_1,2 = 97, 100 ALEBT SCC 4E‐6 mbar
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T. Kalvas
IS03b: RF_trans: 40 kW, 20‐30 mA H‐
variable: SCC P(H2 LEBT)H‐
int. [m
A]‐30 ‐20
‐1
0 0
H‐be
am current
P_LEBT
[1E‐6 H 2]
Co‐extracted
e‐
H
V
RMS
RF_trans: 40 kW
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T. Kalvas
H‐be
am current
P_RF
[kW]
Co‐extracted
e‐IS03b: 20‐30 mA H‐
variable: RF_Trans PowerH‐
int. [m
A]‐20 ‐10
0
Analysis pending;IS03b may provide: 36 mA25 mA Within 0.25 [∙mm∙mrad]27 mA Within 0.3 [∙mm∙mrad]E‐Measured at the center of the LEBT
IS03c tests : October 2016
RMS
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Beam profile (preliminary)
Goal: Position the emittance meter slits at the beam center and measure with the E‐meter grids the beam profile as a function of the Solenoid currents to set a beam size corresponding to the grid dimension (30 mm).
Looks like a hollow beam ! Simulation and analysis of the grid response in a non space charge compensated regime
Vertical Beam profile: Horizontal slit Horizontal wire grid
Horizontal Beam profile: Vertical slit Vertical wire grid
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PIC beam formation
PIC beam formation provides insight to the origin of the H‐ ion Could production on Cs‐surface favour generation of hollow beams Improvement of the CPU power to few micron cell size is a priority
29 mA H‐ simulated with ONIXZ, Z’ plots (perp. to beam axis)
21 mA H‐
Origin: Cs‐Surface 300 A/m28 mA H‐
Origin: Volume
S. Mochalskyy
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D‐ beam form IS03b 16/08/2016
Goal: E‐meas before and during cesiationto differentiate respective emittance distributions
Test Conditions: Magnet and D2 delivery timing scaled with square root of mass ratios (2)
RF_trans: 35 kW Source, puller, Einzel : ‐45, ‐36, 43 kVLEBT: 2‐30 E‐6 mbar H2Before cesiation D‐ 11 mA, e/D =34After cesiation D‐ 22 mA, e/D = 2
D‐ 11 mA, e/D =34
D‐ 22 mA, e/D =2 20 mA
10 mA
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D‐ beam form IS03b16‐17/08/2016
Very first experience with D‐ beam; it differs form H‐production:More electrons are co‐extracted
The cesiation swiftly looses its effect Constant Cs injection improved stability during E‐meas (~1h).
During cw cesiation: D‐ 26 mA, e/D = 4RF‐trans 33 kW
25 mA
0
500
current [ m
A]
e‐dumpSourceEinzel
H‐
200
0
current [ m
A]
33 kW
2011/09/2016
D‐ beam emittance results
D‐be
am current
P_LEBT
[1E‐6 H 2]
Co‐extracted
e‐ 16/08/2016
D‐int. [m
A]‐15 ‐10
‐5
0
PSB Injection
T. Kalvas
RMS
2111/09/2016
IS03‐protons
IBSimu estimated emittance of 0.2 ∙mm∙mradat LEBT entrance for a p‐beam of 100 mA
A puller electrode was added as a tuning parameter
+ 45 kV ‐35 kV
Gnd. Gnd.
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IS03 Proton source: (very‐) preliminary test
Beam Current Transformer
Faraday Cup
‐30 mA cal. pulse
Experimental conditions: • Use of the Einzel lens of
the H‐ optics set at ‐45 kV, 32 mA
• The puller was floating (38 kV, 8 mA)
• Source: +45 kV, ‐131 mA• RFTrans : 24 kW• 71 mA (p + H2
+ + H3+)
Horiz.
Vert.
Sig. V
70 mA
24 kW
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Einzel lens HV‐feed through
Cs‐Oven, Front end and IS‐flange heating jackets
UHV HJ (300°)
Cs‐Oven
Cs‐valve motorization
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Conclusion outlookImportant L4IS WP milestones were achieved: First year of 40‐50 mA H‐ beam operation with monthly cesiation of 3‐4 hours
duration is a succes (IS03a). Automatization of the ion source operation is achieved in the 35‐43 mA range,
Autopilot is the key to meet the 98% availability figure of merit. Simulation of nominal plasma is achieved and was corroborated with OES
measurements The IS03b prototype is installed in the Linac4, H‐ current: 35 mA, 25 mA within
0.25 ∙mm∙mrad and 27 mA within 0.3 ∙mm∙mrad. A spare unit (IS03c) is produced and ready for beam characterization A proton source (backup in the unlikely event of a failure of Linac2) is produced
and ready for emittance measurements, 71 mA (p + H2+ + H3
+). Challenges ahead: The Emittance of the IS03b prototype meets the specification at 25 mA H‐ beam
intensity, the evolution of emittance with intensity is an issue. The emittance data require in depth analysis, the growth along the LEBT is an issue,
can we shorten / remove the LEBT ? The beam may be hollow and the origin (volume / cesiated surface) of H‐ ions has
to be tracked to provide realistic beam formation prediction. Beam diagnostics is a key: Grids & E‐meter require upgrade / automatizationTest: Cs‐Implanted Moly PE, D‐ beam.
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Linac4 IS CollaborationsIPP Garching U. Fantz, S. BriefiUniversity of Jyvaskyla O. Tarvainen, T. KalvasSNS M. Stockli et.al.KEIO University A. Hatayama 畑山明聖
IPGP Orsay T. MineaISIS D. Faircloth BNL J. Alessi J‐PARC A. HuenoCERNJ.P. Corso, J. Coupard, M. Wilhelmsson, F. Fayet, D. Steyeart, E. Chaudet, Y. Coutron, A. Dallocchio, P. Moyret, S. Mathot, Y. Body, R. Guida, P. Carriè, A. Wasem, J. Rochez, D. Aguglia, D. Nisbet, C. Machado, N. David, S. Joffe, P. Thonet, J. Hansen, N. Thaus, P. Chigggiato, A. Michet, S. Blanchard, H. Vestergard, M. Paoluzzi, M. Haase, A. Jones, A. Butterworth, A. Grudiev, R. Scrivens, M. O'Neil, P. Andersson, S. Bertolo, C. Mastrostefano, E. Mahner, J. Sanchez, I. Koszar, U. Raich, F. Roncarlo, F. Zocca, D. Gerard, A. Foreste, J. Gulley, C. Rossi, G. Bellodi, J.B. Lallement, M. Vretenar, A. Lombardi, J.B. Lallement, S. Intoudi, B. Teissandier, C. Charvet, B. Lefort
Matthias Kronberger SLHC‐Fell. CERN
Claus Schmitzer SLHC‐PhD.
Giorgios Voulgarakis Fell.
Anne Despond Dipl.
Daniel Fink Fell.
Jose Sanchez Dipl, Tech‐Fell.
Jaime Gil Flores Tech‐Fell.
Chiara Pasquino Tech‐Fell.
Cristhian Valerio PhD.
Sylvia Izquierdo Tech‐Fell.
Mahel Devoldere Tech‐Fell.
Marco Garlasche Fell.
Serhiy Mochalsky Fell. LPGP Orsay
Taneli Kalvas PhD. Jyvaskyla Univ.
Masatoshi Ohta 太田雅俊 Keio Univ.
Masatoshi Yasumoto 安元雅俊
Kenjiro Nishida 西田健治朗
Takanori Shibata 柴田崇統
Takashi Yamamoto 山本尚史
M. Onai
Shota Abe
Matthew Garland
D Rauner
Thank you all
Stud
ents & Fellows
L4 IS‐team
2711/09/2016