| Paper | Title | Page |
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| MOCO01 | Innovative Schemes of Plasma Heating for Future Multiply-Charged Ions Sources: Modeling and Experimental Investigation | 14 |
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| The application of plasma heating methods alternative to the direct Electron Cyclotron Resonance coupling, such as the Electron Bernstein Waves (EBW) heating, is already a reality in large-size thermonuclear reactors. These plasma waves give the unique opportunity to largely overcome the cutoff density. EBW heating in compact traps such as ECRIS devices is still a challenge, requiring advanced modelling and innovative diagnostics. At Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud (INFN-LNS), the off-ECR heating (driven by Bernstein waves) has produced a highly overdense plasma. Interferometric measurements say the electron density has overcome by a factor ten the cutoff density at 3.76 GHz. More advanced schemes of wave launching have been designed and implemented on the new test-bench called Flexible Plasma Trap, operating up to 7 GHz-0.5 T, in flat/simple mirror/beach magnetic configuration. The paper will give an overview about modal-conversion investigation by a theoretical and experimental point of view, including the description of the diagnostics developed to detect plasma emitted radiation in the RF, optical, soft-X and hard-X-ray domains. | ||
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Slides MOCO01 [13.465 MB] | |
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2016-MOCO01 | |
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| MODO01 | Structural Information on the ECR Plasma by X-ray Imaging | 30 |
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| Precise knowledge on the density distribution of the Electron Cyclotron Resonance Ion Source plasma is needed by several reasons: i) in order to possibly improve the quality parameters of the extracted ion beam (emittance, brightness) strongly linked to the plasma structure, ii) to correctly investigate the recently observed plasma instabilities and/or the implementation of alternative heating methods (e.g. modal conversion) iii) in order to improve the general microwave-to-plasma coupling efficiency, in view of a microwave-absorption oriented design of future ECRIS. The non-destructive spectroscopic diagnostic methods give information always corresponding to an integration over the whole plasma volume. X-ray imaging by pin-hole camera can partly overcome this limitation. We performed volumetric and space resolved X-ray measurements at the ATOMKI ECRIS operated at lower frequencies than usual. The experimental setup in detail and the methods how the working parameters were selected will be shown. The integrated and photon-counting analyses of the collected plasma images show a strong effect of the frequency and magnetic field on the plasma structure and local energy content. | ||
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Slides MODO01 [10.710 MB] | |
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2016-MODO01 | |
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MOFO03 |
Simulations of the ECR-based Charge Breeding Process at INFN: Status and Perspectives | |
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| Since 2012, the INFN ion source group has been undertaking an intense activity on numerical modelling, in the European context of the EMILIE Project until 2014. The work concerns the study of the two main aspects influencing the performances of an ECR-based charge breeder: on one hand, the interaction of the injected 1+ beam with the ECR plasma; on the other hand, the energy coupling to plasma electrons by the microwave field set-up inside the plasma chamber. The first aspect has been addressed by developing a numerical code in a Matlab environment, able to reproduce the capture and thermalization of an ion beam by the ECR plasma. Equations describing the process have been implemented trough the Langevin formalism, including a plasma model of increasing complexity. The second aspect has been studied with the interplay between the 3D solver COMSOL Multiphysics and Matlab, describing the plasma through its fully 3D dielectric permittivity tensor. This paper describes the state-of-the-art of the work on both the fronts: it will show an overview of the beam-plasma interaction, offering some hints for the optimization of already existing devices or for the design of new ones. | ||
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Slides MOFO03 [14.312 MB] | |
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| TUAO01 | The Proton Source for the European Spallation Source (PS-ESS): Installation and Commissioning at INFN-LNS | 39 |
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| A 2.45 GHz ' 0.1 T microwave discharge Proton Source has been designed and assembled at INFN-LNS for the European Spallation Source (PS-ESS) in order to produce pulsed beams of protons up to 74 mA nominal current, at 75 keV of energy, with a transverse emittance containing 99 % of the nominal proton current below 2.25 π mm mrad and a beam stability of ± 2 %. The challenging performances of the machine have triggered specific studies on the maximization of the proton fraction inside the plasma and of the overall plasma density, including dedicated modelling of the wave-to-plasma interaction and ionization processes. The plasma conditioning phase started in July and excellent RF to plasma coupling, more than 99.5% is evident since the beginning. Reflected power fluctuation less than 0.05 % was measured providing a great starting point to reach the beam stability requested by the ESS accelerator. | ||
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Slides TUAO01 [14.571 MB] | |
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2016-TUAO01 | |
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| WEPP15 | Design, Construction and Commissioning of the New Superconducting Ion Source AISHa | 109 |
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| At INFN-LNS a new superconducting ECRIS named AISHa has been designed with the aim to provide highly charged ion beams with low ripple, high stability and high reproducibility, also fulfilling the needs of hospital installations (e.g. L-He free, easy to use, etc.). It is a hybrid ion source based on a permanent magnet hexapole providing 1.3 T on plasma chamber walls, and four superconducting coils for the axial trapping. The axial magnetic system is very flexible in order to minimize the hot electron component and to optimize the ECR heating by controlling the field gradients and the resonance length. The design of the hexapole aimed to minimize the demagnetization due to SC coils. The magnetic system measurement confirmed the effectiveness of the adopted solutions. Innovative solutions have been also implemented as it concerns the RF system design. It will permit to operate in single/double frequency mode, supported by variable frequency high power klystron generators, thus exploiting at the same time the FTE Frequency Tuning Effect and the Two Frequency Heating. The source has been assembled at the INFN-LNS site and the commissioning phase already started. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2016-WEPP15 | |
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| WEPP18 | Innovative Mechanical Solutions for the Design of the High Intensity Proton Injector for the European Spallation Source | 112 |
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| The design of the 2.45 GHz, 0.1 T microwave discharge Proton Source for the European Spallation Source (PS-ESS) has required on-purpose solutions in order to maximize the beam brightness, keeping a very high reliability figure. The mitigation of maintenance issues has been the main guideline through the design phase to maximize the MTBF and minimize the MTTR. The mechanical design has been based on advanced solutions in order to reduce as much as possible the venting time for the plasma chamber, to facilitate the replacement of extraction electrodes and/or plasma chamber, and to simplify any after-maintenance alignment procedure. The paper will describe the strategy which has driven the design phase, the solutions adopted to fulfil the project goals and the results of the assembly phase recently concluded at INFN-LNS with successful first plasma. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2016-WEPP18 | |
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