December 2007ESF-Workshop, Athens, Greece University of Jyväskylä, Department of Physics ECR ion source for the highly charged, intensive ion beams H. Koivisto

December 2007ESF-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 2007ESF-Workshop, Athens, Greece What kind of ion source? Accelerator (linear/cyclotron) gives some boundary condition! - Continues or pulsed beam? - A + or A q+ (low versus high charge states)? - Intensity requirement? - Variety of elements? Charge breeding? Etc... ECRIS

December 2007ESF-Workshop, Athens, Greece Operation principle (ECRIS) 1) Sufficient magnetic field (including correct structure) 2) Electrons rotating in magnetic field 3) Microwaves ECR: Electron Cyclotron Resonance

December 2007ESF-Workshop, Athens, Greece Scaling laws (magnetic, frequency) 1) Magnetic field: Axial magnetic field B axial by solenoids Radial magnetic field B radial by multipole VENUSVENUS 14 GHz : 0.5 T 28 GHz: 1 T

December 2007ESF-Workshop, Athens, Greece Scaling laws 2) Frequency R. Geller proposed: as high microwave frequency as possible is wanted! PROBLEM: Higher magnetic field is required!!

December 2007ESF-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 2007ESF-Workshop, Athens, Greece The requirements of next generation heavy ion facilities made the development of 3 rd Generation sources (and maybe 4 th Generation) ECR ion sources necessary SC-ECRIS, RIKEN, Japan VENUS, 270 eµA U 33+ and 270 eµA U 34+ SPIRAL 2, GANIL, France SECRAL, Lanzhou, China H. Zhao MS ECRIS GSI, Germany SuSI NSCL,USA 525 eµA U eµA U 41+ 1mA Ar 12+

December 2007ESF-Workshop, Athens, Greece

December 2007ESF-Workshop, Athens, Greece Optimization of the VENUS source for Ar 12+ to demonstrate the ‘tuning’ of the plasma parameters ArVENUS (28GHz) eμA Motivation: 1mA Ar 12+ for the SPIRAL II Project

December 2007ESF-Workshop, Athens, Greece Comparison of different generations 1st generation:I tot <1 mA 2nd generation:I tot = 2-4 mA 3rd generation:I tot = 10 mA Beyond present technological know-how! B ecr = 2 T B inj ~ 8 T B ext = 4 T B rad = 4 T ECRIS-56

December 2007ESF-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 generation ECRIS (3.5 generation) 4th generation ECRIS requires a lot of development work for example in the field of superconductive technique

December 2007ESF-Workshop, Athens, Greece Some engineering current densities

December 2007ESF-Workshop, Athens, Greece Peak field Solenoid22 T Dipole13 T Quadrupole10 T tested (4.5 T pole) Sextupole + Solenoid Need ~14T for 56 GHz Different Nb 3 Sn-structures

December 2007ESF-Workshop, Athens, Greece From Claude Lyneis Cryocooler Flange LN 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 Bore Plasma Chamber Bremsstrahlung will be a serious problem!

December 2007ESF-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 2007ESF-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 be invested in this work (very visible role during FP7)

December 2007ESF-Workshop, Athens, Greece High temperature ovens: - inductively heated oven (above 2000˙C) Different methods:

December 2007ESF-Workshop, Athens, Greece - resistively heated oven (above 2000˙C)) - sputtering (some refractory elements) - laser ablation?

December 2007ESF-Workshop, Athens, Greece Beam transport More beam intensity from the cyclotron is needed for 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 2007ESF-Workshop, Athens, Greece Statistics (2004) 2nd harmonic JYFL 14 GHz ECRIS Transmission efficiency decreases when beam intensity increases! Some reasons: 1) space charge effect (strong focusing) 2) Emittance increases with beam intensity I cycl /I ECR

December 2007ESF-Workshop, Athens, Greece DIMAD simulations (by X. Wu) Beam spot in viewer according to DIMAD-simulations Beam spot in viewer (just after dipole)

December 2007ESF-Workshop, Athens, Greece Hollow beam JYFL NSCL

December 2007ESF-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 new and exotic beams available

December 2007ESF-Workshop, Athens, Greece Thanks to the following for providing slides for this presentation: - Santo Gammino - Daniela Leitner - Claude Lyneis - Marc Doleans