cyclotron resonance charge breeder and prospects EURISOL TOWN MEETING Pisa July 24th 2018 1 T Thuillier J Angot LPSC R Vondrask ANL L Maunoury P Delahaye ID: 787557
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Slide1
Advances with Electron cyclotron resonance charge breeder - and prospects -
EURISOL TOWN MEETING, Pisa, July 2-4th 2018
1
T. Thuillier , J. Angot, LPSCR. Vondrask, ANLL. Maunoury, P. Delahaye, M. Dubois, GANILA. Galata, SPES, LNLF. Ames, TRIUMF
Slide2Electron Cyclotron Resonance Ion Source Charge BreederA modified ECR Ion Source accepting
1+ ionsHot electrons, cold ions
Step by step ionization
2z
B
z
Axial and Radial
Magnetic
field
B
ECR
RF
Iso-B
lines
R
esonance
1
+
N
+
Magnetized
plasma
Follows
field
lines
Buffer
gas
RF
1
+
N
+
Slide3ECRIS CB Ion CaptureCoulomb collision→ thermalisation
→diffusion →capture
3
Potential
(V)
Low
dens
. Plasma
Te < 100 eV
ECR Zone
Potential
Dip
E
lectrostatic
(~1-10 V)
Ion confinement
1
+
N
+
Dense plasma
Te> 1
keV
Pure
Gas
Injection
(O
2
, He,H
2
)
microwaves
HV
ground
ground
Slide4ECR Charge Breeders in the World4
facility
ECR
CB typestatus CARIBU, Argonne, MI, USAA-ECRstoppedISAC, TRIUMF, CanadaPHOENIXUnder operationLPSC, France
PHOENIXUnder
operation, R&D
SPES, LNL,
ItalyPHOENIXUnder
operation
SPIRAL1,GANIL, France
PHOENIX
Under construction
Texas A&M,
College
station, TX, USA
A-ECR
Under
operation
TRIAC,
KEK- JAERI, JapanKEK-CBFacility closed
Slide5Today ECRIS CB technologyBased on 20 years old 14 GHz ECRIS design
Vacuum~10
-7
down to 10-8 mbar (plastic o-rings, non bakeable)Material facing plasma : stainless steel, low carbon steel, aluminum alloy, copper…=> contamination (gas, condensable sputtering)5A ECR (ANL)
PHOENIX BOOSTER
(LPSC, GANIL, TRIUMF, SPES)
Slide6Orders of MagnitudesSignal to Noise ratio
is a key parameter for ECRIS CB usage:
14 GHz ECR
Itotal~1 mA(~ Buffer gas~
Wall
sputtering
~
whole
ion
spectrum
~
within
1+ signal
N
+ signal
Contaminants within
Gases contaminants~
within
Signal (pps)
Signal/Noise0.010.11
10100
N+ RIB fraction0.9%9%50%91%99%Signal (pps)Signal/Noise0.010.1110100N+ RIB fraction0.9%9%50%91%99%For estimate
Slide7Status of Today ECRIS CB ResearchPROS
Robust
CW operation1+
Intensity up to 1-10 pµA1+N+ Efficiency~4-25% CB time ~1-20 ms/charge stateLIMITSBeam contamination from the source walls~ 103 -104 pps background noiseA/Q~3 up to A=50A/Q~7 up to A=1507Performances are based on 20 years old ion source designsCAN ECRIS CB BE ENHANCED? YES!
Slide8ECRIS CB efficiencies8
Slide9Status of ECRIS CB In the world
Slide10ECRIS CB at SPIRAL1 upgradeCollaboration with ANLCARIBU feedbak
experience used to modify
the SPIRAL1 PHOENIX Booster
Vacuum optimization Plug injection symétriqueAluminium walls2 RF portsCollaboration with LPSCExperimental commissioning tests at LPSCsuccessful10InjectionExtractionBooster
Slide11GANIL-SPIRAL1 upgradeSPIRAL1 Facility restarted in March 2018P. Delahaye, L. Maunoury, M. Dubois et al.
11
3) post
acceleration CIME cyclotronNanogan3 TIS unmounted in the caveECR CB
1+ OR N+ TIS
FC13
FC81
FC11
1) RIB Production
1+ FEBIAD TIS
(condensables
)
N+ Nanogan3
(
gas
)
2) Charge state adaptation
PHOENIX ECR Charge Breeder
Slide12SPIRAL1 upgrade: operation modes« Shooting Through » mode for gaseous
elements
12
Transport efficiencyLEBT(FC81/13)CIME (FC11/81)TotalBEFORE UPGRADE80%20%16%AFTER UPGRADE46%42%17%
ECR
N+
14
O
4+
@26kV
FC13
FC81
FC11
14
O
4+
@7.67MeV/A
1st RIB
produced
with
Nanogan3 TIS: 14O4+ECR CB OFF14O4+ send through itGlobal transmission efficiency keptCIME cyclotronM/M~1000
Slide13SPIRAL1 upgrade: operation modes1+N+ Mode : Charge breeding in the ECR Ion SourceFirst beam: 37
K1+ charge bred to 37K
9+ with an efficiency of 5.3%
Preliminary (short test RUN)Measured on an ID station13Booster FEBIAD TIS
37
K
1+
Identification
station
37
K
9
+
Slide14SPIRAL1 upgrade: operation modesECR Charge greeder used as a standard ion s
ource to produce stable beam into
CIMESaving power to GANILFast energy
changeIndustrial applications and astrophysics14Stable Ion BeamRequirementBoosterE72536Ar @3.2MeV/A36Ar7+ @15kVEM9784Kr @2MeV/A84Kr @5MeV/A84Kr @7MeV/A84Kr11+@14,3kV84Kr17+ @21.5kV84Kr20+ @28.8kVEM97129Xe @2,5MeV/A129Xe @5MeV/A129Xe @7MeV/A129Xe22+ @13.3kV129Xe22+ @26.6kV129Xe27+ @32.7kV
ECR CB
Slide15SPES ADIGE Injector15
Medium
Resolution Mass
SpectrometerM/ M~1000 (150 kV HV Platform) ECRIS CBStable 1+ SourceElectrostatic LEBTMagnetostatic LEBTPost accelerationUnder installation
Slide16SPES ADIGE Injector
1+ stable beam test 09/2018Stable 1+N+ Test : 06/2019
16
Post acceleration1+ Source cage
Dipoles
Magnetic
triplets
Electrostatic
triplets
Successful FAT
Slide17SPES:
Beam Purity R&D
First Action: R&D on reductions
of contaminantsAgreement LNL-LPSC under discussionTests on the LPSC test benchDesign, construction and test of 2 Aluminum plasma chambersAnalysis of contamination induced by SS and AlTest of hot and cold liners to mitigate the contaminant yieldNb, Ta or W17Hot linersCold linersplasma chamber
Slide18SPES : Beam Purity IssuesPossible clean beams
available for post-accelerationAssuming
worst conditions of contaminationand separation
18POSSIBLE RIBs FOR POST-ACCELERATIONWITH CONVENTIONAL MATERIAL26AlContaminated by 13C, 26Mg, 52Cr, 78Kr: other materials for chamber94RbContaminated by 94Mo (SS)130SnPossible clean peaks at 19+,29+132SnPossible clean peaks at 19+,21+,23+132Sb
132
Te
134
Te
Possible clean peaks at 27+,31
+
138
Cs
Possible clean peaks at 20+,22+,23+,26+,28+,30+,31+
POSSIBLE RIBs FOR
POST-ACCELERATION
WITH LINERS R&D
26
Al
Still problems
due to
13
C, 78Kr: to be checked after vacuum cleaning94RbPossible clean peaks at 15+,16+,21+130SnPossible clean peaks at 19+,22+,27+,29+,32+132SnPossible clean peaks at 19+-21+,23+-25+,30+-32+132Sb132Te134TePossible clean peaks at 22+,26+,27+,28+,33+138CsPossible clean peaks at 20+,22+-26+,28+,32+Beams of interest
R&D
LINERS SHOULD INCREASE CHARGE STATES AVAILABILITY
Slide19Recent R&D at LPSCDone with the PHOENIX Booster on the 1+N+ test bench
19
Slide20Plasma stability and background level
Plasma k
inetic instabilities transiently
generate a huge plasma potential Vp~1 kVStrong sputtering from the wall Peak identification shows: stainless steel plasma chamber composition: Fe, Cr, Mo, Ni, Al, Zn, Cu, MnElectrodes composition (Al alloy 2017): Al, Cu, Mn, ZnRelease of previous condensed 1+ beam (Cs,Rb,K)20stableunstableJoint study with JYFL & IAP RAS
Slide21Magnetic confinement upgradeImproving axial magnetic field
trap had important effects
Axial magnetic field
profile: no plug: plugNew plugSoft iron
plug
High
efficiency
increase
For
low
masses
Higher
charge state
7%
efficiency
With
rise
time
<10 ms/Q
Slide22Short 1+ pulse StudyStudy transient plasma and possible 1+ ion accumulation effect
on the buffer gas plasma
The time to extract 90% of the N+ ions <
traditional CB time by ~10%No noticeable accumulation effect was observed221+N+Integral90%long 1+ pulse
Slide23CARIBU ECRIS CB TestamentAfter an intensive research on background reduction
, the ECRIS CB was stopped at Argonne and replaced
by an EBISthe RIB signal (
pps)was lower than the ECRIS ion background and the mass resolution of the downstream accelerator () was not sufficient to reduce significantly the background<3% RIB content in the accelerated beam on the target 23ECRIS swampEBIS pool
Slide24CARIBU ECRIS CB TestamentExample of 146Ba done
with the ECRIS2.7% of RIB content in the beam
with
100% RIB would need or RIB intensity increased by 2424
68
Zn
13+
47
Ti
9
+
94
Mo
18+
94
Zr
18+
120
Sn
23+
136
Xe
26+
146Ba28+193Ir37+
198Hg38+
3
% of total beam current
198
Hg
38+68Zn13+146Ba26+197Ir36+120Sn23+94Mo18+
Slide25CARIBU ECRIS TestamentMany techniques experimented to reduce the ECRIS beam background :
CO2 snow cleaningAluminum
coating
25Reduction factorCO2 cleaningAL coatingF20160Cl417Fe50Not detectableAr-22%3
Slide26CARIBU ECRIS CB TestamentAtomic Layer DepositionCreating a thick conformal
homogeneous coatingBuit
atomic Layer by atomic layer An Al203 layer
could be deposited on all the parts located under vacuum26Atomic LayerDeposition (ALD)SlowCoats all sidesConformal
200 nm
ZnO
Si
Slide27Binary Reaction Sequence for Al2O3 1 ALD Cycle of TMA/H2
O Deposits 1 Al2O3 “Monolayer”
27
Al
CH3
CH
3
CH
3
OH
OH
OH
Al
CH
3
CH
3
CH
3
A)
B)
OH
Al
(CH
3
)
3
OH
OH
Trimethyl Aluminum
(TMA)
CH
4
Al
CH
3
Al
CH
3
CH
3
H
2
OAlCH3CH3CH3OHOH
OH
Al
CH
3
Al
CH
3
CH
3
Al
CH
3
CH
3
CH
3
CH
3
OH
OH
OH
Al
Al
CH
3
CH
3
H
2
O
H
2
O
OH
CH
4
OH
OH
Slide28CARIBU ECRIS TestimonyNew ECR3 permanent magnet source is being installedPossibility to prototype ALD system for use with this sourceWill provide proof of principle with minimal disruption to operations
28
Slide29TRIUMF ECRIS CBPHOENIX BOOSTER purchased from PantechnikU
nder operation at TRIACModified by TRIUMF
2 stage ion injection & extractionAl coating
29plasma chambermagnet yoke
Slide30TRIUMF: A/Q selection with Nier type spectrometer30
ion optical simulation for mass resolution after charge state breeding
ΔM/M > 200
Slide31LINAC chain used as mass filter31
Before final filtration
After final filtration
94Mo/Rb/Sr132Xe119Sn113In107Ag69Ga
94Mo/Rb/Sr
using LINAC chain as mass filter (M/
ΔM≈1000)additional stripping at 1.5 MeV/u to 94Rb
22+
laser ionized
94
Sr:
Sr:Rb
= 3:1
charge bred to
94
Sr
15+
1·10
7
ions/s (~1.5%)
accelerated and delivered
to TIGRESS experimentParticle ID from ΔE-E after acceleration(M. Marchetto et al. proceedings LINAC2012, JACoW.org)
Slide32TRIUMF CB Results32
Results:
ECR charge state breeder at ISAC operational since 2008
isotopes from more than 15 elements have been charge bred so farrange of ions charge bred for acceleration: 21Na – 160Er Efficiency per charge state 1-5%problems: high background long breeding time (~20 ms*q)Outlook:improvements to ECR charge breeder → Joseph AdegunEBIS charge breeder → Brad Schultz158Er
Slide33ECR CB Prospects
Slide34Prospect: Improve the ion captureOptimize the capture with a denser and a longer
and plasmaToday, a part of the 1+ beam
is not captured, even
some 2+ and 3+ are ionized on flight and not captured (10-20% lost)34
1
+
1
+
2
+
3
+
10-20%
Non
captured
ions
Slide35Prospect: Improve the ion capture
Lengthening the ECR plasma of the booster at 14 GHz from 14 cm to 40 cm would
grant a 99% 1+ captureAt higher
frequency (eg: 18 GHz) 25 cm plasma is necessary to capture all the 1+35unefficient1+ capture100%1+ captured
Slide36Long ECRIS plasma already existsRIKEN SC ECRIS 18-28 GHz can generate
flat magnetic field
36
Prospect: Reduce the CB timeECR frequency
scaling law : no limit
so far up to 28 GHz operationPlasm
a density : Charge Breeding Time: Today, standard ECR CB
are operated at
14 GHz
An 18 GHz ECR CBwould reduce
by -40%
A
28
GHz ECR
CB
would
reduce
by
-75%
With
respect to 14GHz operation 37-40%-75%todayGreat time Reduction BUT it would increase the background from the wall as Only suitable for very high RIB intensity
Slide38Prospect: Increase the mean N+ ion charge state
Optimize the magnetic confinement using
up to date know-howLarger plasma chamber
radius Demonstated with PHOENIX V2V3 upgrade (SPIRAL2)Larger plasma chamber lengthWith an optimized ECR CB:Xe42+ (A/Q~3 ; A=132)U42+ (A/Q~6 ; A=238) 38V2V3
B
z
B
r
z
r
Slide39Prospect: Reduce ion contaminationGeometrical background reduction
by dilutionContaminant density
A 40 cm ECR plasma
length and 30 cm diameterwould reduce the background by a factor of 5 at 14 GHzUse a pure material for everything facing the plasmaMuch less background peakspossible bakeable materials : Titanum, Niobium, TantalumGet rid of gas contaminantFully Bakeable source, UHV technique H2 or He Gas injection purified with a cryo pumpIt is worth making a R&D on background reduction in ECRIS CB
39
Prospect for EURISOL
Superconducting
ECR CB @
14
GHz
NbTi@4 K
plasma
chamber
pure
Ti or
Nb or Ta
Thermal
screen
And
Water
cooled
300°Surface
Heater
wire
to
bake
out
The plasma
chamber
Online up to 300°C
HV
insulator
Plasma
chamber
Ø300
mm
L1200
mm
Long
ECR
Plasma
Slide41THANK YOU FOR YOUR ATTENTION