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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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Acceleration of carbon ion beams by an ultraviolet laser under conditions relevant for ion fast ignition of inertial fusion
摘要： The properties of carbon ion beams produced by a 100-kJ, 1-ps, KrF ultraviolet laser under conditions relevant for ion fast ignition (IFI) of DT fusion are numerically investigated using the 2D3V particle-in-cell code, and the possibility of achieving the ion beam parameters required for IFI is tested. The numerical simulations of carbon ion acceleration were carried out for ?at carbon targets of various thicknesses (LT) and for various laser beam apertures (dL) on the target, while the laser pulse duration and energy were ?xed. It was found that both the radiation pressure acceleration (RPA) mechanism and the sheath acceleration mechanism signi?cantly a?ects the characteristics of the ion beam, with the RPA dominating in the case of thicker targets (LT ～ 10–30 μm). The ion beam parameters depend to a signi?cant extent on the target thickness and the distance from the target. The mean and maximum ion energy decrease with the increase of LT from 3 μm to 30 μm, while the ion beam intensity, the beam energy ?uence and the total energy of the “useful part” of the ion beam (with an aperture ≤ 50 μm) reach maximum values at LT ～ 5–10 μm. For the optimal value of LT and a small distance x from the target (x ～ LT), the ion beam parameters are close to or higher than what is required for IFI. However, due to the angular divergence of the ion beam, the beam intensity and ?uence decrease with an increase in the distance from the target, and at x ≥ 0.5 mm the beam parameters are below the values required for fusion ignition. To reach these values, higher laser energies and/or more sophisticated schemes of ion acceleration are required.
关键词： Ion sources,Accelerator Applications,Accelerator modelling and simulations
更新于2025-09-19 17:13:59
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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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Irradiation and dosimetry arrangement for a radiobiological experiment employing laser-accelerated protons
摘要： The Bragg Peak is a unique characteristic of ion beams which makes their use beneficial in cancer treatment as it allows the majority of dose deposition to be localised in a precise volume. The use of a laser system for particle acceleration is currently investigated as a potential alternative to the conventional RF accelerators currently used for hadrontherapy. The biological response of cells irradiated by high dose-rate laser-driven ions is currently being explored in this context. The experiment reported here was carried out as part of the A-SAIL project, a UK-wide collaboration aiming to develop innovative techniques for accelerating ions for future clinical applications. In this contest, a radiobiological experiment was carried out on the pico2000 laser beamline at LULI-école Polytechnique using an energetically spread, laser-accelerated proton beam. This paper will discuss the arrangement used in the experiment, and the techniques employed for an accurate estimation of the dose deposited, supported by Monte Carlo simulations of the particle propagation through the irradiation system.
关键词： Ion sources,Lasers,Radiation damage evaluation methods
更新于2025-09-12 10:27:22
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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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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