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Characterization of ECR plasma by means of radial and axial X-ray diagnostics
摘要： This work presents the X-ray characterization of the plasma generated in a simple mirror axis symmetric trap as a function of the magnetic field profile. A Si-Pin detector has been used to characterize warm electron population in axial and radial directions at 6.83 GHz. Moreover, the hot electrons emitted in axial direction has been measured by means of a HyperPure Germanium (HpGe) detector. Results show that X-ray emission is not homogenous, and its homogeneity and temperature depend strongly on the magnetic field profile, and especially on the Bmin/BECR ratio.
关键词： Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)),Solid state detectors,X-ray detectors
更新于2025-09-23 15:22:29
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Proton beams of laser-hydrogenated metal targets
摘要： In this paper, we report a study on proton beams produced via laser interaction from hydrogenated solid targets useful for the development of new sources devoted to medical applications, such as hadron therapy and isotope production. The hydrogenation of the targets was made before the laser-matter interaction. In this study, we used as solid targets, pure samples of Ti, Ta and Al which in a ?rst phase were treated by laser cleaning (via KrF excimer laser at the irradiance I = 3×107 W/cm2) and then they were exposed to laser irradiation (1500 pulses, I = 3×107 W/cm2) under a constant ?ow of H2 (HiQ Hydrogen 6.0, highly pure). After that, the targets were maintained under H2 ?ow for 5 minutes, in order to promote a further hydrogen adsorption. We report laser ablation measurements performed at ?uences of 1.3, 2.5 and 5.0 J/cm2. The results on hydrogenated targets showed an increase of proton yield of 25% (Ti), 64% (Al) and 550% (Ta), with respect to the corresponding untreated ones.
关键词： Plasma generation (laser-produced, RF, x ray-produced),Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)),Accelerator Applications
更新于2025-09-19 17:13:59
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Laser absorption spectroscopy studies to characterize Cs oven performances for the negative ion source SPIDER
摘要： The SPIDER H?/D? ion source is currently in operation in the Neutral Beam Test facility (NBTF) at Consorzio RFX (Padova, Italy) to prove the possibility of generating up to 40 A of negative ions, with a maximum extracted current density of 350 A/m2 (H)/285 A/m2 (D) and a fraction of co-extracted electrons not greater than 0.5 (H)/1 (D). These performances are required for the realization of the ITER Neutral Beam Injector (NBI), which should deliver 16.7 MW to the plasma by means of negative ions accelerated up to 1 MeV and neutralized before being injected into the ITER tokamak. In order to obtain such high extracted current densities and low co-extracted electron fractions it is necessary to lower the work function of the surface of the acceleration system grid facing the source; this will be accomplished by coating the surfaces with Cs, routinely evaporated by three ovens. The functionality of the ovens has been tested at the CAesium oven Test Stand (CATS), hosted at NBTF. The test stand is equipped with several diagnostics, among which a Laser Absorption Spectroscopy (LAS) diagnostic. Using a tunable laser diode, the LAS diagnostic gets the high resolution absorption spectrum of the Cs 852 nm D2 line along a line of sight to measure Cs density at ground state. The paper describes the test stand and the LAS diagnostic, together with the characterization of the ovens to be installed in SPIDER. The paper will also study the systematic density underestimation e?ect caused by Cs ground state depopulation, as a function of laser intensity and of Cs density, in the perspective of correcting the density evaluation.
关键词： Plasma diagnostics - interferometry, spectroscopy and imaging,Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS))
更新于2025-09-16 10:30:52
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Multi-diagnostic setup to investigate the two-close-frequency phenomena
摘要： While the mechanism is still not fully 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 space-resolved spectroscopy and by probing the rf signals emitted by the plasma. Concerning the characterization of the X radiation, 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.
关键词： Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)),X-ray detectors,Plasma diagnostics - interferometry, spectroscopy and imaging,Plasma generation (laser-produced, RF, x ray-produced)
更新于2025-09-09 09:28:46
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Numerical Identification of Trivelpiece–Gould Waves in an Electron Cyclotron Resonance Etching Reactor
摘要： Electron cyclotron resonance (ECR) plasma sources have been widely used for ultra-large-scale integration manufacturing processes because of their wide operating range and excellent uniformity over 300- or 450-mm diameter wafer. However, microwave electromagnetic fields in magnetized plasma-filled reactors are not well understood because of the complexity of electromagnetic wave field analysis. We conducted microwave electromagnetic field analysis of an ECR plasma etcher by the finite-element method using a simulation platform. Complicated electric field patterns were clearly observed under some conditions. We investigated the patterns in detail to determine whether they were spurious or not. The patterns proved to be Trivelpiece–Gould waves according to their characteristics imposed by the dispersion relation of waves. This analysis approach is a powerful method because very fine-wave structures can be identified.
关键词： Electron cyclotron resonance (ECR),plasma sources,etching,Trivelpiece–Gould (TG) waves
更新于2025-09-09 09:28:46
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Redesign of the GANIL GTS ECRIS for 1+/n+ studies
摘要： More than half of the beams produced at GANIL are metallic elements, underlining the importance of their continuing development. Compared to the conventional techniques (oven, sputtering, MIVOC), the 1+/n+ method has demonstrated superior ionization e?ciencies, suggesting the potential for improved metal beam production. Dedicated studies are required to assess the feasibility of this approach. The SPIRAL1 Charge Breeder is now in operation at the GANIL radioactive beam facility SPIRAL1. Operation in high radiation area poses challenges for its future development. A separate test stand supporting charge breeder and metal ion beam R&D is thus desirable. The GTS 14.5 GHz ECRIS has been chosen as a platform for 1+/n+ studies. After the upgrade program of 2017–2018, the GTS provides good performance and versatility, making it well-suited for ion source R&D. A new injection module has been designed for 1+ injection into the GTS plasma to be used in the 1+/n+ studies. It can be easily replaced with the conventional system for normal ion source operation. The design of the new injection system will be presented in detail with ion optical simulations of the 1+ beam injection.
关键词： Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS),Beam Optics
更新于2025-09-04 15:30:14
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High resolution spectropolarimetry: from Astrophysics to ECR plasmas
摘要： 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. Understanding and further developing magnetic traps requires accurate measurements of the physical properties of the con?ned plasma, such as density, temperature and ionization state, not allowed by the commonly used diagnostic methods (imaging, low resolution spectroscopy). Here, we show the potentiality of a few diagnostic applications of high resolution spectroscopy in the visible range, routinely used in Astrophysics to measure stellar physical parameters such as e?ective temperature, surface gravity, chemical abundances. In addition, we show that polarimetry is a powerful technique to derive the morphology of stellar magnetic ?elds, whose knowledge is necessary for a correct interpretation of spectra from magnetized plasmas. An application of these non-invasive methods to B-min ECR plasma concerning optical emission is discussed in view of a better understanding of the plasma structure, magnetic con?nement properties and heating processes.
关键词： Plasma diagnostics - charged-particle spectroscopy,Polarisation,Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS))
更新于2025-09-04 15:30:14