Author: Mascali, D.
Paper Title Page
MOB3 Commissioning of the AISHA Ion Source at INFN-LNS 10
 
  • L. Celona, G. Castro, F. Chines, S. Gammino, O. Leonardi, D. Mascali, M. Mazzaglia, L. Neri, G. Torrisi
    INFN/LNS, Catania, Italy
 
  The AISHa ion source has been designed to generate high brightness multiply charged ion beams with high reliability, easy operations and maintenance for hadrontheraphy applications. Aisha is a compact ECRIS whose hybrid magnetic system consists of a permanent Halbach-type hexapole magnet and a set of independently energized superconducting He-free coils. The present work shows the results of the ion source commissioning in SFH operational mode (18 GHz) for different ion species. Current status and further improvements will be highlighted.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-MOB3  
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TUB2 Plasma Heating and Innovative Microwave Launching in ECRIS: Models and Experiments 63
 
  • G. Torrisi, G. Castro, L. Celona, S. Gammino, D. Mascali, G. Mauro, M. Mazzaglia, E. Naselli, G. Sorbello
    INFN/LNS, Catania, Italy
  • A. Galatà
    INFN/LNL, Legnaro (PD), Italy
  • E. Naselli
    Catania University, Catania, Italy
 
  Microwave-to-plasma coupling in ECRIS has been based on the classic scheme of waveguide-to-cylindrical plasma cavity matching. Optimization has been often obtained by empirical adjustments leading to an oversimplified model, obtaining however satisfying performances. In order to overcome the ECR-heating paradigm, on-purpose design of launchers' setup adequate diagnostics have to be developed. This paper describes three-dimensional numerical simulations and Radio Frequency (RF) measurements of wave propagation in the microwave-heated magnetized plasmas of ion sources. Moreover, driven by an increasing demand of high frequency ECR ion sources, innovative ideas for the geometry for both the plasma chamber and the related RF launching system - in a plasma microwave absorption-oriented scenario are presented. Finally, the design of optimized launchers enabling single-pass power deposition, not a'ected by cavity walls effects, are described.  
slides icon Slides TUB2 [50.695 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUB2  
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TUB3 A Possible Optimization of Electron Cyclotron Resonance Ion Sources Plasma Chambers 67
 
  • C.S. Gallo, A. Galatà
    INFN/LNL, Legnaro (PD), Italy
  • D. Mascali, G. Torrisi
    INFN/LNS, Catania, Italy
 
  In the resonant cylindrical cavities of Electron Cyclotron Resonance Ion Sources (ECRIS), microwave fields are used to generate and sustain the plasma. Normally, resonant modes of a higher order than the fundamental one are excited, due to the high frequency used compared to the dimensions of the plasma chambers: this can lead to small electric fields on the resonant surface, translating in low electrons energy and poor source performances. In this paper, we propose a possible modification of the conventional plasma chambers, resulting from an electromagnetic study carried out on a Caprice-type full permanent magnet ECRIS. Such modification implies the excitation of a "length-independent" resonant mode, having an intense and homogeneous electric field on the plasma chamber axis. This characteristic makes the modification suitable to be applied to numerous ECR sources. The positive effect on the plasma electrons density distribution will be also shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUB3  
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TUP02 An Irradiation Test Facility at INFN-LNS: Status and Perspectives 75
 
  • G.G. Rapisarda, V.P. Bonanno, R. Catalano, G.A.P. Cirrone, L. Cosentino, G. Cuttone, D. Mascali, M.S. Musumeci, G. Petringa, S.M.R. Puglia, D. Rifuggiato, S.T. Salvatore
    INFN/LNS, Catania, Italy
 
  In the framework of ASIF "ASI Supported Irradiation Facilities" project some beamlines available at Laboratori Nazionali del Sud-INFN (LNS) Catania have been dedicated to irradiation test. These beamlines have been recently upgraded in order to meet the ESA specifications about radiation hardness testing of devices suitable for space applications. The Superconducting Cyclotron K800 installed at LNS can provide protons up to 80 MeV for integrated dose tests and a number of heavy ion beams for Single Event Effect (SEE) studies. The beamlines are equipped with detectors that allow beam diagnostic in term of spatial uniformity, purity and energy measurement, including on-line monitoring of flux and fluence received by the device under test. Upgrades activities are now ongoing, especially to broaden up the number of available beams, both in terms of ion species and energy, to optimize the switching times from one beam to another. The paper will present an overview of the developed facility, which will take benefit of the ongoing SERSE (the superconducting ECR ion source) revamping: the new gas-box system, plasma chamber and controls system are ready to be installed within autumn 2018.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUP02  
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TUP11 The First Measurement of Plasma Density by Means of an Interfero-Polarimetric Setup in a Compact ECR-Plasma Trap 102
 
  • E. Naselli, G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, G. Sorbello, G. Torrisi
    INFN/LNS, Catania, Italy
  • E. Naselli
    Catania University, Catania, Italy
  • G. Sorbello
    University of Catania, Catania, Italy
 
  This paper presents the first measurement of plasma density by a K-band microwave polarimetric setup able to measure the magnetoplasma-induced Faraday rotation in a compact size plasma trap. The polarimeter, based on rotating waveguide OMTs (OrthoModeTransducers), has been proven to provide reliable measurements of the plasma density even in the unfavorable conditions 'p ' Lp ' Lc (being 'p, Lp and Lc the probing signal wavelength, the plasma dimension and the plasma chamber length respectively) that complicates the measurements due to multi-patterns caused by reflections of the probing wave on the metallic walls of the plasma chamber. An analysis method has been developed on purpose in order to discriminate the polarization plane rotation due to magnetoplasma Faraday rotation only, excluding the effects of the cavity resonator. The measured density is consistent with the previous plasma density interferometric estimations. The developed method is a powerful tool for probing plasmas in very compact magnetic traps such as Electron Cyclotron Resonance Ion Sources and for in-plasma '-radionuclides' decay studies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUP11  
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TUP12 Results of the Optical Emission Spectroscopy diagnostics of the ESS proton source 107
 
  • G. Castro, L. Celona, S. Gammino, O. Leonardi, D. Mascali, M. Mazzaglia, A. Miraglia, E. Naselli, L. Neri, R. Reitano, G. Torrisi
    INFN/LNS, Catania, Italy
  • E. Naselli
    Catania University, Catania, Italy
  • R. Reitano
    Università degli Studi di Catania, Catania, Italy
 
  The high intensity proton source for the European Spallation Source, designed and commissioned at INFN-LNS, is able to produce a stable total current between 40 and 125 mA through an 8 mm extraction aperture, with a proton fraction up to 87%. The best source condition for PS-ESS requirements has been investigated by means of the Optical Emission Spectroscopy (OES). OES has permitted to evaluate simultaneously the H/H2 relative abundances together with electron density and temperature. Results demonstrated that high intensity proton beams are generated in overdense plasma conditions (around 1018 m-3 electron density measured by OES), while electron temperature shows a decreasing trend with power. The results will be discussed and compared with Faraday-cup and Doppler shift measurements. Further upgrades of OES diagnostics will be highlighted.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUP12  
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TUP13 Characterization of ECR Plasma by Means of Radial and Axial X-Ray Diagnostics 111
 
  • R. Miracoli
    ESS Bilbao, Zamudio, Spain
  • G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, E. Naselli, G. Torrisi
    INFN/LNS, Catania, Italy
  • E. Naselli
    Catania University, Catania, Italy
 
  This work presents the X-ray characterization of the plasma generated in simple mirror axis symmetric trap as a function of magnetic field profile. A Si-Pin detector has been used to characterize warm electron population either in axial than in radial direction at two different operating frequencies: 4.1 GHz and 6.8 GHz. Moreover, the hot electrons emitted by axial direction has been measured by means of a HyperPure Germanium (HpGe) detector. Results show that X-ray emission is not homogenous and homogeneity and temperature depends strongly on the magnetic field profile.  
poster icon Poster TUP13 [1.422 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUP13  
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TUP14 Multi-Diagnostic Setup to Investigate the Two-Close-Frequency Phenomena 115
 
  • S. Biri, Z. Perduk, R. Rácz
    ATOMKI, Debrecen, Hungary
  • C. Caliri, G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, E. Naselli, F.P. Romano, G. Torrisi
    INFN/LNS, Catania, Italy
  • A. Galatà
    INFN/LNL, Legnaro (PD), Italy
  • J. Pálinkás
    University Debrecen, Debrecen, Hungary
  • F.P. Romano
    IBAM-CNR, Catania, Italy
 
  While the mechanism is still not clear, the beneficial effect (higher intensity of highly charged ions, stable plasma conditions) of the second microwave injected to the ECR plasma was observed in many laboratories, both with close and far frequencies. Due to the complexity of the phenomena (e.g. interaction of resonant zones, damped instabilities) complex diagnostic methods are demanded to understand its mechanism better and to fully exploit the potential hidden in it. It is a challenging task since complex diagnostics methods require the arsenal of diagnostic tools to be installed to a relatively small size plasma chamber. Effect of the injected second 13.6-14.6 GHz microwave to the 14.25 GHz basic plasma has been investigated by means of soft and (time-resolved) hard X-ray spectroscopy, by X-ray imaging and by probing the rf signals emitted by the plasma. In order to separate the source and position of different X-ray photons special metallic materials for the main parts of the plasma chamber were chosen. A detailed description and explanation of the full experimental setup and the applied non-invasive diagnostics tools and its roles are presented in this paper.  
poster icon Poster TUP14 [2.615 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUP14  
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TUP25 Study of the Influence of Magnetic Field Profile on Plasma Parameters in a Simple Mirror Trap 144
 
  • M. Mazzaglia, G. Castro, L. Celona, S. Gammino, D. Mascali, E. Naselli, R. Reitano, G. Torrisi
    INFN/LNS, Catania, Italy
  • R. Miracoli
    ESS Bilbao, Zamudio, Spain
  • E. Naselli
    Catania University, Catania, Italy
  • R. Reitano
    Università degli Studi di Catania, Catania, Italy
  • S.B. Stefan, U.F. Ursel
    MPI/IPP, Garching, Germany
 
  This work presents the multiple diagnostics characterization of the plasma in an axis-symmetric simple mirror trap as a function of magnetic field profile (mirror ratios and magnetic field gradient), neutral gas pressure and microwave power. The simultaneous use of Optical Emission Spectroscopy, Langmuir Probe and X-ray diagnostics allows the characterization of the whole electron energy distribution function (EEDF), from a few eV to hundreds of keV. Results show non-linear behaviours under small variations of even one source parameter and strong influence of EEDF on the Bmin/BECR ratio. Benefit and next developments will be highlighted.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUP25  
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TUP27 Numerical Simulations of Magnetically Confined Plasmas 152
 
  • A. Galatà, C.S. Gallo
    INFN/LNL, Legnaro (PD), Italy
  • D. Mascali, G. Torrisi
    INFN/LNS, Catania, Italy
 
  Since 2012, the INFN ion source group has been undertaking an intense activity on numerical modelling of magnetically confined plasmas, presently carried out in the framework of the PANDORA project. The aim is the development of a predictive tool for the design of Electron Cyclotron Resonance (ECR) Ion Sources or Traps and ECR-based Charge Breeders, able to determine spatial density and energy distributions for both electrons and ions. The work mainly concerns the study of two aspects: on one hand, the interaction of an ion beam with a magnetized plasma; on the other hand, the microwave-to-plasma coupling, including the 3D plasma electrons dynamics in the confinement magnetic field and intra-particles collisions. This contribution describes the state-of-the-art of the work on both the fronts: an overview of the beam-plasma interaction, showing the latest results about the ECR-plasma density fine structure, as well as electron spatial temperature distribution will be shown.  
poster icon Poster TUP27 [1.254 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-TUP27  
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WEA4 Time Resolved X-Ray Measurements in a Simple Mirror Trap 162
 
  • S.T. Salvatore, C. Altana, G. Castro, L. Celona, S. Gammino, G.L. Lanzalone, G.L. Litrico, D. Mascali, M. Mazzaglia, A.M. Muoio, E. Naselli, G. Torrisi
    INFN/LNS, Catania, Italy
  • R. Miracoli
    ESS Bilbao, Zamudio, Spain
  • E. Naselli
    Catania University, Catania, Italy
 
  The time-resolved characterization of the X-ray emission represents an innovative technique to investigate the heating mechanism of the worm/hot electron component in ECRIS devices. In this paper, the technique has been described and the results of an experimental campaign of measurements in order to characterize the X-rays emission of an axis-symmetric simple mirror trap has been showed. Particular attention has been paid to the ignition and turning off phase. This approach has permitted to estimate confinement time of the warm/hot electron population and put in evidence eventual instability effects during the critical phases. Further developments and perspectives of the technique will be highlighted.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-WEA4  
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WEA5 Effect of the Two-Close-Frequency Heating to the Extracted Ion Beam and to the X-Ray Flux Emitted by the ECR Plasma 165
 
  • R. Rácz, S. Biri, Z. Perduk
    ATOMKI, Debrecen, Hungary
  • G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, E. Naselli, G. Torrisi
    INFN/LNS, Catania, Italy
  • A. Galatà
    INFN/LNL, Legnaro (PD), Italy
  • J. Pálinkás
    University Debrecen, Debrecen, Hungary
 
  Multiple frequency heating has been used since the '90 in ECR ion sources as heating schemes able to improve current intensities especially for highly charged ions. More recently, "Two Close Frequency Heating", where the frequency gap is comparable with the scale-length of the resonance, has been proposed, expected also to be sensitive to the relative waves phase relationship. At ATOMKI - Debrecen a dedicated experiment has been carried out for exploring the effects of the combined frequencies and their relative phase-difference in an argon plasma. The second frequency was finely tuned between 13.6-14.6 GHz with respect to the first one (fixed 14.25 GHz). An optimal frequency gap (in terms of Ar11+/A6+ beam currents ratios) has been experimentally found, in agreement with the theory; the optimal power balance (total RF power was 200 W) between the two frequencies has been determined empirically. A weak but clear effect of the relative phase shift has been observed. Each configuration has been characterized by a multi-diagnostics set-up: HPGe and SDD detectors were used for the X-rays, a RF probe was introduced inside the plasma chamber to detect the radio-emission from the plasma.  
slides icon Slides WEA5 [4.394 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-WEA5  
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THA1
High Intensity Proton Source and LEBT for the European Spallation Source  
 
  • L. Celona, G. Calabrese, G. Castro, F. Chines, S. Gammino, O. Leonardi, G. Manno, D. Mascali, M. Mazzaglia, A. Miraglia, L. Neri, G. Torrisi
    INFN/LNS, Catania, Italy
 
  At the Istituto Nazionale di Fisica Nucleare ' Laboratori Nazionali del Sud (INFN-LNS) the beam commissioning of the high intensity Proton Source (PS-ESS) and the Low Energy Beam Transport (LEBT) line for the European Spallation Source (ESS) has been completed. The official project schedule was satisfied and the source has been installed in the ESS accelerator tunnel on January 2018. Due to the high flexibility of the magnetic system, and to the innovative approach developed for the commissioning, we were able to test a huge amount of configurations (more than 400'000). The optimum source configuration that satisfy all requirements at the same time has been identified. The source is able to produce a stable total current between 40 and 125 mA (90 mA requested) through an 8 mm extraction aperture, with a proton fraction of up to 87%. At the end of the LEBT the beam characteristics fully satisfy the ESS requirements: more than 70 mA of proton beam with 99% normalized beam emittance of 2.25 '.mm.mrad have been transported with intra pulse current fluctuation below ±1.5% and long term current fluctuation below ±3%. Results and used strategy are shown in details.  
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FRA3 High Resolution Spectropolarimetry: From Astrophysics to ECR Plasmas 209
 
  • M. Giarrusso, G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, E. Naselli
    INFN/LNS, Catania, Italy
  • G. Avila
    ESO, Garching bei Muenchen, Germany
  • G. Del Zanna
    University of Cambridge, Cambridge, United Kingdom
  • E. Landi
    University of Michigan, Ann Arbor, Michigan, USA
  • F. Leone
    Università degli Studi di Catania, Catania, Italy
  • F. Leone, M. Munari
    INAF-OACT, Catania, Italy
  • E. Naselli
    Catania University, Catania, Italy
 
  Electron Cyclotron Resonance (ECR) plasmas with high density and high temperature are required by the injectors for the Accelerators and by interdisciplinary studies in Astrophysics and Nuclear Astrophysics. The magnetic traps need a very fine analysis of plasma conditions in terms of density, temperature and ionisation state, not allowed by the present diagnostic methods (imaging, low resolution spectroscopy not spatially resolved). We here describe the results routinely obtained in Astrophysics with high resolution spectroscopy, largely used to analyse astrophysical plasmas in the visible range, which allows to determine physical parameters of stars as surface gravity, effective temperature, chemical abundances. In addition we show that polarimetry is the only technique to derive the morphology of stellar magnetic fields, whose knowledge is necessary for a correct interpretation of spectra from magnetised plasmas. An application of these non-invasive methods to minimum-B ECR plasma concerning optical emission is discussed in view of a better comprehension of the plasma structure, magnetic confinement properties and heating processes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-FRA3  
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FRB2 Impact of the Two Close Frequency Heating on ECRIS Plasmas Stability 214
 
  • E. Naselli, C. Caliri, G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, F.P. Romano, G. Torrisi
    INFN/LNS, Catania, Italy
  • S. Biri, Z. Perduk, R. Rácz
    ATOMKI, Debrecen, Hungary
  • A. Galatà
    INFN/LNL, Legnaro (PD), Italy
  • E. Naselli
    Catania University, Catania, Italy
  • J. Pálinkás
    DU, Debrecen, Hungary
  • F.P. Romano
    IBAM-CNR, Catania, Italy
 
  Several experiments have recently demonstrated that plasma instabilities are powerful limiting factors to the flux of highly charged ion beam extracted from ECRIS. One of the methods for damping the instabilities is to feed the plasma in two frequency heating mode. Since the fundamental physical mechanism is still unclear (diffusion in velocity space? additional confinement?), a deeper experimental investigation is necessary, using multi-diagnostics setups. At ATOMKI-Debrecen the effect on the plasma instabilities of an argon plasma in a 'Two Close Frequencies' scheme has been explored. Spectra of radio-emission from the plasma have been collected for different frequency gaps and relative power balances. The measurements show the plasma self-emitted radiation comes out from the internal plasma (i.e. around the lower frequency) but the instability damping can be effective for some specific combinations of frequency-gap and power balance. Radiofrequency spectra have been collected simultaneously to time-resolved X-ray measurements, triggered by RF bursts produced by the instabilities and detected via a microwave diode connected to a plasma-chamber-immersed multi-pin RF probe.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-FRB2  
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