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University of Jyväskylä, Department of Physics. ECR ion source for the highly charged, intensive ion beams. H. Koivisto. Content. 1. Production of highly charged ion beams (by ECRIS). 2. Present projects and challenges. 3. (Metal) Ion beam production. 4. Beam transport. - PowerPoint PPT Presentation
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December 2007 ESF-Workshop, Athens, Greece
University of Jyväskylä, Department of Physics
ECR ion source for the highly charged, intensive ion beams
H. Koivisto
December 2007 ESF-Workshop, Athens, Greece
Content
1. Production of highly charged ion beams (by ECRIS)
2. Present projects and challenges
3. (Metal) Ion beam production
4. Beam transport
December 2007 ESF-Workshop, Athens, Greece
What kind of ion source?
Accelerator (linear/cyclotron) gives some boundary condition!
- Continues or pulsed beam?
- A+ or Aq+(low versus high charge states)?
- Intensity requirement?- Variety of elements? Charge breeding? Etc...
ECRIS
December 2007 ESF-Workshop, Athens, Greece
Operation principle (ECRIS)
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1) Sufficient magnetic field (including correct structure)
2) Electrons rotating in magnetic field
3) Microwaves
ECR:ElectronCyclotronResonance
December 2007 ESF-Workshop, Athens, Greece
Scaling laws (magnetic, frequency)
1) Magnetic field: Axial magnetic field Baxial by solenoids
Radial magnetic field Bradial by multipole
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VENUS
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14 GHz : 0.5 T
28 GHz: 1 T
0
1
2
3
4
-100 -50 0 50 100
Solenoid Field on axisSextupole only
Ion Source Axis [cm]
December 2007 ESF-Workshop, Athens, Greece
Scaling laws
2) Frequency
€
Iq ∝ f 2
R. Geller proposed:
as high microwave frequency as possible is wanted!
PROBLEM: Higher magnetic field is required!!
December 2007 ESF-Workshop, Athens, Greece
ECRIS generations
1st generation: 6.4 GHz MSU RT-ECRIS, TAMU 6.4 GHz, etc
2nd generation: 14 GHz ECRIS AECR, Artemis, Caprice, etc.
3rd generation: 28 GHz VENUS, SECRAL, several under
construction: Requires SC-technique!
December 2007 ESF-Workshop, Athens, Greece
The requirements of next generation heavy ion facilities made the development of 3rd Generation sources (and maybe 4th Generation) ECR ion sources necessary
SC-ECRIS, RIKEN, Japan
Post Accelerator
Isotope Separator
Fragmentation Production Target
Fragmentation Separator
Driver Linac (400 MeV/nuc U, 900 MeV p)
RFQ’s
Experimental Areas
“Gas Catcher”
Nuclear Structure
In Flight Separation
IsotopeRecovery
E< 15 MeV/u E>50 MeV/u
Applied Physics
Astro Physics
E< 1 MeV/u
No Acceleration
VENUS, 270 eµA U33+ and 270 eµA U34+
SPIRAL 2, GANIL, France
SECRAL, Lanzhou, China
H. Zhao
MS ECRISGSI, Germany
SuSINSCL,USA
525 eµA U35+
50-100 eµA U41+
1mA Ar12+
December 2007 ESF-Workshop, Athens, Greece
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December 2007 ESF-Workshop, Athens, Greece
Optimization of the VENUS source for Ar12+ to demonstrate the ‘tuning’ of the plasma parameters
Ar VENUS(28GHz)
eμA
12+ 86014+ 51416+ 27017+ 3618+ 1
0
200
400
600
800
2 3 4 5 6 7 8 9
Analyzed Current [eµA]
Mass to Charge
O3+
O4+
10
O5+
O6+
15
9
8
7
1112
13
14
16
O2+
6
Motivation: 1mA Ar12+ for the SPIRAL II Project
December 2007 ESF-Workshop, Athens, Greece
Comparison of different generations
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1st generation:Itot<1 mA
2nd generation:Itot= 2-4 mA
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Beyond present technological know-how!
Becr= 2 T Binj ~ 8 TBext= 4 TBrad= 4 T
ECRIS-56
December 2007 ESF-Workshop, Athens, Greece
MS-ECRIS won’t be a 4th generation ECRIS even if 56 GHz can be tested
It won’t fulfill the scaling law for the magnetic fields!
It will be a step between the 3rd and 4th generationECRIS (3.5 generation)
4th generation ECRIS requires a lot of development workfor example in the field of superconductive technique
December 2007 ESF-Workshop, Athens, Greece
Some engineering current densities
0
100
200
300
400
500
600
0 5 10 15 20 25B Tesla
Je A/mm
2
Nb3Sn at 4.2K
NbTi at 1.9K
NbTi at 4.2K
B2212 at 4.2K
B2212 at 35K
December 2007 ESF-Workshop, Athens, Greece
Peak field
Solenoid 22 T
Dipole 13 T
Quadrupole 10 T tested (4.5 T pole)
Sextupole+ Solenoid
Need ~14T for 56 GHz
Different Nb3Sn-structures
December 2007 ESF-Workshop, Athens, Greece
From Claude LyneisCryocoolerFlangeLN Reservoir
(70 K)
LHe Reservoir (4.2 K)
50 K Shield
Cold Mass
with Coils Enclosed
Links Iron Yoke
Vacuum Vessel
Cryostat and Cold Mass
• Bremsstrahlung created in collisions of energetic electrons with the plasma chamber walls produce a high flux of x-rays.
• A fair amount of this energy is deposited in the cryostat
• With the original Al plasma chamber:
• 1 W/kW 28 GHz (only 2 W cooling power available)
• 150mW/kW for 18 GHz
• High voltage insulation deteriorates in the high x-ray flux
Warm BorePlasma Chamber
Bremsstrahlung will be a seriousproblem!
December 2007 ESF-Workshop, Athens, Greece
Challenges for 4th generation ECRIS
- superconducting wire to reach required B-field
- bremsstrahlung (heating of cryostat)
- cooling of plasma chamber (power up to tens of kW)
- efficient extraction to handle multi tens of mA beam
- coupling of microwaves to plasma
December 2007 ESF-Workshop, Athens, Greece
Production of metal ion beams
ECOS working group: “In order to meet the requirements of the future experiments with high-intensity beams, further development is needed,
especially in the production of metal-ion beams. Consequently, the development of ECR ion source will be one of the most
active areas in accelerator physics.”
Consequently a lot of human resources will beinvested in this work (very visible role during FP7)
December 2007 ESF-Workshop, Athens, Greece
High temperature ovens:
- inductively heated oven (above 2000˙C)
Different methods:
December 2007 ESF-Workshop, Athens, Greece
- resistively heated oven (above 2000˙C))
- sputtering (some refractory elements)
- laser ablation?
December 2007 ESF-Workshop, Athens, Greece
Beam transport
More beam intensity from the cyclotron is neededfor the experiments!!
Improvement of ECRIS performance does not always increase the intensity for the experiments
beam formation or/and transmission problem!!Problem in several laboratory!
December 2007 ESF-Workshop, Athens, Greece
Statistics (2004)Total transmission efficiency
0,00
0,02
0,04
0,060,08
0,100,12
0,14
0,16
0,18
0 25 50 75 100 125 150 175Intensity [µA] 14 GHz ECRIS
Efficiency2nd harmonic
JYFL 14 GHz ECRIS
Transmission efficiency decreases when beam intensityincreases!
Some reasons: 1) space charge effect (strong focusing)2) Emittance increases with beam intensity
Icycl/IECR
December 2007 ESF-Workshop, Athens, Greece
DIMAD simulations (by X. Wu)
Beam spot in viewer according to DIMAD-simulations
Beam spot in viewer (just after dipole)
December 2007 ESF-Workshop, Athens, Greece
Hollow beam
JYFL
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NSCL
December 2007 ESF-Workshop, Athens, Greece
“ECOS” needs the development of:
- ion sources for higher intensity and higher charge states
- beam formation to produce high quality beams
- high quality beam transport facility to transport beam efficiently to accelerator
-development of metal ion beam production to make newand exotic beams available
December 2007 ESF-Workshop, Athens, Greece
Thanks to the following for providing slides for this presentation:
- Santo Gammino - Daniela Leitner - Claude Lyneis
- Marc Doleans