Abstract Simulations are a powerful method to study the correlation between output beams and internal dynamics of electron cyclotron resonance ion sources (ECRIS), which involve a complex interplay ...between injected power, RF frequency, gas type and pressure. We present here some details on 3D full-wave Particle-in-Cell (PIC) code suites that can simulate electron and ion dynamics self-consistently in an ECR plasma. Preliminary runs of the simulation show an encouraging match with experimental data which acts as a benchmark for the PIC codes and highlights its potential for fundamental and applied interdisciplinary plasma research.
The Capuchin Catacombs of Palermo, Italy, contain over 1800 mummies dating from the 16th to 20th centuries AD. Their environment is not conducive to the conservation of the remains due to, among ...other factors, water infiltration, which is producing salt efflorescences on the walls. A multiphasic approach was applied to investigate the halophilic microbiota present in the Catacombs. Enrichment cultures were conducted on media containing different NaCl concentrations, ranging from 3 to 20 %. For screening of the strains, the following two PCR-based methods were used and compared: fluorescence internal transcribed spacer PCR (f-ITS) and random amplification of polymorphic DNA (RAPD) analyses. Results derived from RAPD profiles were shown to be slightly more discriminative than those derived from f-ITS. In addition, the proteolytic and cellulolytic abilities were screened through the use of plate assays, gelatin agar and Ostazin Brilliant Red H-3B (OBR-HEC), respectively. Many of the strains isolated from the wall samples displayed proteolytic activities, such as all strains belonging to the genera
Bacillus
,
Virgibacillus
and
Arthrobacter,
as well as some strains related to the genera
Oceanobacillus
,
Halobacillus
and
Idiomarina.
In addition, many of the strains isolated from materials employed to stuff the mummies showed cellulolytic activities, such as those related to species of the genera
Chromohalobacter
and
Nesterenkonia
, as well as those identified as
Staphylococcus equorum
and
Halomonas
sp. Furthermore, many of the strains were pigmented ranging from yellow to a strong pink color, being directly related to the discoloration displayed by the materials.
Abstract
Resistive oven technique is used to inject vapours of metallic species in electron cyclotron resonance (ECR) plasma traps, where plasma provides step-wise ionization of neutral metals, ...producing charged ion beams for accelerators. We present a numerical survey of metallic species suitable for oven injection in ECR ion sources, studying neutrals diffusion and deposition under molecular flow regime. These aspects depend on geometry of the evaporation inlet, thermodynamics, and plasma parameters, which strongly impact on ionization and charge-exchange rate, thus on the fraction of reacting neutrals. We considered diffusion of metals with and without plasma. The plasma and its parameters have been modelled considering an established self-consistent particle-in-cell model. Numerical predictions might be relevant to reduce the metal consumption, to increase the overall efficiency, and to improve the plasma ion source performances. As test case, we studied the
134
Cs isotope, as one of the alkali metals of interest for the modern nuclear physics.
Electron cyclotron resonance ion sources (ECRIS) are the most efficient ion sources among those used in facilities for nuclear physics with stable and exotic beams, because of their ability to ...generate intense beams of medium charge state ions, or moderate intensities at high and very high state of charge (hundreds of eμA of U 33+ o Xe 34+ ). Their development has been based primarily on semi-empirical laws (High-B mode plus frequency scaling), which link the performances in terms of current and produced charge state distribution to the magnetic field (that provides the ion confinement in the plasma) and to the frequency of microwaves (used for plasma heating). A further scaling in field and frequency, to access larger extracted current and charge states, involves a considerable impact on the ion sources complexity and cost, probably exceeding the technological limits for superconducting magnets. The experience gained in the last decade produced an understanding of some new mechanisms of plasma production in ECRIS, highlighting the main weaknesses of the previous model. Additional requirements such as the improvement of stability and reliability or the minimization of beam-current ripple require a perfect knowledge of the plasma heating mechanism, to be obtained via experimental and theoretical work, accompanied by adequate plasma and beam diagnostics. We will review hereinafter the basis of the so-called "standard model" for ECRIS beam production along with the new ideas that in the coming years may disclose the path towards further improvements.
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.
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