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PANDORA, Plasmas for Astrophysics, Nuclear Decays Observation and Radiation for Archaeometry, is planned as a new facility based on a state-of-the-art plasma trap confining energetic plasma for ...performing interdisciplinary research in the fields of Nuclear Astrophysics, Astrophysics, Plasma Physics and Applications in Material Science and Archaeometry: the plasmas become the environment for measuring, for the first time, nuclear decay rates in stellar-like condition (such as
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Be decay and beta-decay involved in s-process nucleosynthesis), especially as a function of the ionization state of the plasma ions. These studies will give important contributions for addressing several astrophysical issues in both stellar and primordial nucleosynthesis environment (
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, determination of solar neutrino flux and
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Li Cosmological Problem), moreover the confined energetic plasma will be a unique light source for high-performance stellar spectroscopy measurements in the visible, UV and X-ray domains, offering advancements in observational astronomy. As to magnetic fields, the experimental validation of theoretical first- and second-order Landé factors will drive the layout of next-generation polarimetric units for the high-resolution spectrograph of the future giant telescopes. In PANDORA new plasma heating methods will be explored, that will push forward the ion beam output, in terms of extracted intensity and charge states. More, advanced and optimized injection methods of ions in an ECR plasma will be experimented, with the aim to optimize its capture efficiency. This will be applied to the ECR-based Charge Breeding technique, that will improve the performances of the SPES ISOL-facility at Laboratori Nazionali di Legnaro-INFN. Finally, PANDORA will be suitable for energy conversion, making the plasma a source of high-intensity electromagnetic radiation, for applications in material science and archaeometry.
Electron cyclotron resonance ion sources based charge breeders (ECR-CB) are fundamental devices for Isotope Separation On Line (ISOL) facilities aiming at postaccelerating radioactive ion beams ...(RIBs). Presently, low intensity RIBs do not allow a conventional tuning of the ECR-CB: as a consequence, it has to be set with a stable 1+ pilot beam first, switching then to the radioactive one without changing any parameter; this procedure is usually called “blind tuning.” Besides having different masses, pilot and radioactive beams can also differ in terms of the rms transverse emittance εrms and/or longitudinal energy spread ΔE , so the choice of a given pilot beam can determine the overall performances of the final breeding stage. This paper shows a numerical study of how the capture efficiency of the PHOENIX charge breeder is affected by the aforementioned beam paramaters: the analysis reveals the two-step nature of the process, highlighting the role of the injection optics and the plasma capture capability in the overall performances of this device. The simulations predict highest efficiency for εrms<5πmmmrad and ΔE<5eV in a optimum energy range between 2 and 6 eV, thus giving important information on the possibility of blindly tuning an ECR-CB. No isotopical effects were observed, while it clearly came out the necessity to improve the 1+ beam characteristics with a rf beam cooler prior to the injection into an ECR-CB.
Abstract The cooling of secondary beams is important for accelerator-based nuclear physics. In the radiofrequency (RF) quadrupole cooler (RFQC), RF fields and ion-gas collisions may give a ...considerable increase or decrease of the beam transverse emittance and energy spread, depending on a delicate tuning of heating and cooling effects, dominated by the ion beam kinetic energy and the balance of collisions and confinement forces. An extra confinement may be added by a solenoid magnetic field, as in the RFQC prototype installed in the Eltrap machine. This provides a versatile test bench (distinct from a closed accelerator installation) for detailed studies of cooling dynamics and of several RFQC technical optimizations (for gas differential pumping and bias voltages). Modeling concepts and simulation results are summarized. The major RFQC parameters are reviewed, in particular for 133 Cs + collisions against He gas whose pressure p g ranges from 2 to 9 Pa in the reference case, with attention to the extraction, comparing triode/tetrode system, and to the bias voltages. Lower bias voltages request less p g , but provide less cooling of the energy spread.
Aim of the PANDORA (Plasmas for Astrophysics, Nuclear Decays Observation and Radiation for Archeometry) project is the in-plasma measurements of decay rates of beta radionuclides as a function of the ...ionization stage. In this view, a precise calculation of plasma electrons density and energy is mandatory, being responsible for ions’ creations and their spatial distribution following plasma neutrality. This paper describes the results of the INFN simulation tools applied for the first time to the PANDORA plasma, including electromagnetic calculations and electrons’ dynamics within the so-called self-consistent loop. The distribution of the various electrons’ population will be shown, with special attention to the warm component on which depends the obtained ions’ charge state distribution. The strict relation of the results with the evaluation of the in-plasma nuclear decays will be also explained.
Abstract
One possible way to optimize microwave coupling and plasma confinement in Electron Cyclotron Resonance (ECR) Ion Sources is a revolutionary design strategy of plasma chambers, breaking the ...cylindrical symmetry. This contribution reports about the design and numerical validation of an innovative resonant cavity playing as plasma chamber of ECR ion sources. The new chamber, named IRIS (Innovative Resonators for Ion Sources), was argued starting from the 3D structure of the plasma and, therefore, fashioned to the twisting magnetic structure. The microwave launching scheme was radically changed as well, consisting of side-coupled slotted-waveguides with diffractive apertures smoothly matching the overall structure of the camera. This approach also enables a profound optimization of cooling systems and overall spaces in general (for gas feedings, oven systems, sputtering, etc.). Here we report on the conceptual study, electromagnetic design and PIC simulations of the electron heating in the novel resonant cavity, comparing results with those for standard (cylindrical) chamber, and also considering the impact of microwave feeding led by single aperture rectangular waveguides vs. waveguide-slotted antennas. Manufacture strategy, based on additive manufacturing techniques, will also be discussed.
Abstract An innovative ECR ion trap facility, called PANDORA (Plasma for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry), was designed for fundamental plasma processes and ...nuclear physics investigations. The overall structure consists of three subsystems: a) a large (70 cm in length, 28 cm in inner diameter) ECR plasma trap with a fully superconducting B-minimum magnetic system (B max = 3.0 T) and an innovative design to host detectors and diagnostic tools; b) an advanced non-invasive plasma multidiagnostics system to locally characterize the plasma thermodynamic properties; c) an array of 14 HPGe detectors. The PANDORA facility is conceived to measure, for the first time, in-plasma β -decaying isotope rates under stellar-like conditions. The experimental approach consists in a direct correlation of plasma parameters and nuclear activity by disentangling - by means of the multidiagnostic system that will work in synergy with the γ-ray array - the photons emitted by the plasma (from microwave to hard X-ray) and γ-rays emitted after the isotope β -decay. In addition to nuclear physics research, fundamental plasma physics studies can be conducted in this unconventional ion source equipped with tens of detection and diagnostic devices (RF polarimeter, optical emission spectroscopy (OES), X-ray imaging, space and time-resolved spectroscopy, RF probes, scope), with relevant implications for R&D of ion sources for accelerator physics and technology. Several studies have already been performed in downsized nowadays operating ECRIS. Stable and turbulent plasma regimes have been described quantitatively, studying the change of plasma morphology, confinement, and dynamics of losses using space resolved X-ray spectroscopy.
Abstract Metals can be injected into electron cyclotron resonance ion sources (ECRIS) via different techniques, among which resistive ovens are used to vaporize neutral materials, later captured by ...the energetic plasma that will step-wise ionize them, hence giving multiply charged ion beams for accelerators. Recently, PANDORA, a novel ECR plasma trap, has been conceived to perform interdisciplinary research spanning from nuclear physics to astrophysics, where in-plasma high charge states of metallic species are demanded. However, a full knowledge on the vaporization method and on the coupling of neutral atoms with plasma and its overall dynamics is still not available. Simulations, hence, are of fundamental relevance to improve the overall efficiency, reduce consumption of rare expensive isotopes, and to improve the ion source performance. We present a numerical study about metallic species suitable for oven injection in ECRIS, focusing on metals diffusion, transport, and wall deposition under molecular flow regime. We studied the metal dynamics with and without plasma. Results underline the plasma role on a space-dependent conversion yield, reflecting the strongly inhomogeneous ECR plasma. The plasma and its parameters have been modelled using an established self-consistent particle-in-cell model. The numerical tool is conceived for the PANDORA plasma trap but can be extended to other ECR plasmas and traps. As test cases we studied the 134 Cs and 48 Ca radioisotopes, as metals of interest for the modern nuclear physics. A focus is given on the β -decaying 134 Cs, as an application case for PANDORA, providing quantitative estimates of the γ-detection signal-poisoning effect by neutral metals deposition at the chamber wall.
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