Abstract An innovative plasma chamber for Electron Cyclotron Resonance Ion Sources (ECRIS) has been developed at INFN and will soon be installed and tested with the AISHa (Advanced Ion Source for ...Hadrontherapy) ion source. It consists in inserting a particular liner into the existing chamber, which allows an electrical segmentation of the internal walls of the chamber. The purpose of this system is to reduce the ion losses induced by the anisotropic diffusion mechanism, to improve the plasma confinement and thus to increase the overall performance of the ion source. In fact, in ECRIS plasmas, electrons mostly diffuse along magnetic field lines while ions mostly leak across the same lines. In particular, the inner walls of the plasma chamber are covered with 30 tiles, each one polarized to a proper positive voltage. The tiles are made of Al-6082 and anodized except for the surface directly facing the plasma. The anodizing process makes each tile electrically insulated from the others and from the plasma chamber while preserving the correct operation of the cooling system. The tiles are wrapped by 2 half-cylinders made of Al-6082 acting as shells. Some tiles are equipped of a temperature sensor and machined to allow the wiring of the entire system. In this work the results of the preliminary tests of the thermal and electrical behaviour of the active chamber and the future perspectives are presented.
The AISHa ion source at INFN-LNS Castro, G.; Celona, L.; Chines, F. ...
Journal of physics. Conference series,
04/2022, Letnik:
2244, Številka:
1
Journal Article
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Abstract
The Advanced Ion Source for Hadrontherapy (AISHa) is an ECR ion source operating at 18 GHz, developed with the aim of producing high intensity and low emittance highly charged ion beams for ...hadrontherapy purposes. Due to its unique peculiarities, AISHa is a suitable choice for industrial and scientific applications. In the framework of the INSpIRIT and IRPT projects, in collaboration with Centro Nazionale di Adroterapia Oncologica (CNAO), new candidates for cancer treatment (including metal ion beams) are being developed. Moreover, within the IONS experiment, AISHa will be the test-bench for the development of an innovative active plasma chamber designed to increase plasma confinement by changing plasma fluxes. OES technique will be also used to refine techniques of non-invasive plasma diagnostics. Finally, a dedicated setup is under realization to provide impinging beams and detection systems for target production in nuclear physics experiments.
The linear electromagnetic interaction between innovative hybrid metallo-dielectric nanostructured targets and laser in visible and IR range is investigated through numerical simulations. The ...obtained results rely on the optimization of a target based on metallic nanowires (NWs) to enhance light absorption in the visible range of the electromagnetic spectrum. The NWs are grown within the ordered nanoholes of an alumina substrate, thus, forming a plasmonic lattice with triangular symmetry. The remaining volume of the nanoholes on top of the NWs is sealed with a transparent layer of aluminum oxide that is suitable to be chemically modified for containing about 25% of deuterium atoms. The study presented here is carried out within the framework of a scientific program named PLANETA (Plasmonic Laser Absorption on Nano-Engineered Targets) aiming at investigating new laser–matter interaction schemes in the ns domain and for nuclear fusion purposes, involving especially the D–D reaction.
Auxiliary electrons can be successfully used as a diagnostic probe to deduce characteristics and dynamics of magnetically confined plasmas typical of Electron Cyclotron Resonance and Microwave ...Discharge Ion Sources, as well as to improve their performances and/or stability. To this scope, numerical simulations are a powerful tool to predict the effect of the interaction of an electron beam with the plasma: this paper presents an alternative way to deduce the plasma density by joining the results of numerical simulations with the diagnostic of the beam transmitted through the plasma. As will be shown, the applied numerical code is able to describe the dynamics of an electron beam, generated by an e-gun, propagating inside a plasma trap, with a magnetic configuration typical of microwave discharge ion sources, focusing on several effects such as ionizations, heating, space charge etc. The role played by the position of the e-guns with respect to the magnetic field profile will be also underlined.
This work aim to prepare a program of studies on nuclear physics and astrophysics, which will be conducted at the new ELI-NP Laser facility, which actually is under construction in Bucharest, ...Romania. For the arguments treated, such activity has required also a multidisciplinary approach and knowledge in the fields of nuclear physics, astrophysics, laser and plasma physics join with also some competences on solid state physics related to the radiation detection. A part of this work has concerned to the experimental test, which have been performed in several laboratories and in order to study and increase the level of knowledge on the different parts of the project. In particular have been performed studies on the laser matter interaction at the ILIL laboratory of Pisa Italy and at the LENS laboratory in Catania, where (by using different experimental set-ups) has been investigated some key points concerning the production of the plasma stream. Test has been performed on several target configurations in terms of: composition, structure and size. All the work has been devoted to optimize the conditions of target in order to have the best performance on the production yields and on energies distribution of the inner plasma ions. A parallel activity has been performed in order to study the two main detectors, which will constitute the full detections system, which will be installed at the ELI-NP facility.
Electron cyclotron resonance (ECR) ion sources are largely used for production of intense beams in science and industry. Performances of modern devices are severely limited by the generation of ...suprathermal electrons, whose origin is still controversial. We hereby demonstrate that the electron energy distribution function is strongly influenced by the reciprocal displacement of magnetic field and plasma density profiles. The latter can be modified independently of the former, e.g. by changing the plasma anisotropic diffusion. Auxiliary electrons emitted by carbon nanotube based electron guns are used for Simon current compensation: this significantly reduces the ion losses, increases the output currents and successfully suppresses the hot electron generation.
An investigation of the effects of substrate type and various treatments on carbon nanotubes (CNT) growth, using an evaporated Ni thin film as a catalyst, is presented. Barrier layers of SiO
2, Si
3N
...4, and TiN on Si were used as substrates. The catalyst-insulating substrate systems have been processed in several gaseous atmospheres (Ar, NH
3 and H
2) and in the temperature range 700–900
°C, in order to obtain the most appropriate morphology, size and density of catalyst particles as seeds for the subsequent CNT growth. On this kind of substrates, the smallest nanoparticles were obtained on SiO
2 layers, in H
2 or NH
3 atmosphere even at 700
°C. However, the best vertically aligned and well-graphitized CNT resulted from the NH
3 annealing process, followed by the CNT deposition at 900
°C in C
2H
2 and H
2.
On TiN conducting substrates, the best vertically aligned CNT were deposited using a shorter annealing step and a deposition process at reduced pressure. The samples were characterized by means of scanning electron microscopy (SEM) and Raman spectroscopy analysis.
Field Emission (FE) properties of vertically aligned Carbon Nanotubes (CNTs) grown in a nanoporous anodic aluminium oxide (AAO) template have been investigated. A 50-μm-thick AAO template was ...fabricated by electrochemical techniques. The nanotubes were synthesized in a CVD quartz hot wall furnace using C
2H
2/N
2 mixtures as feeding gas.
I–V measurements have been performed on samples after the nanotubes growth (type I samples) and after a partial Al
2O
3 removal (type II samples) in order to obtain segments of nanotubes protruding from the nanopores. The effects of the conditioning process and adsorbates release have been investigated. The emission curves have been analysed in the framework of the Fowler–Nordheim model. For the
β factor enhancement, a different dependence on time has been evidenced for two types of investigated samples and has been tentatively correlated with materials modifications occurring under the HV polarisation (in case of type I samples) and with the damage induced by chemical etching (in case of type II samples). The values of emitted current density (up to 40
mA/cm
2) and the emission properties indicate that the proposed preparation methodology is suitable for the realization of robust and efficient CNT-based field emission devices and electron sources.
Different electrochemical regimes and porous alumina were applied for template synthesis of cobalt nanowire (nw) arrays, revealing several peculiar cases. In contrast to quite uniform filling of ...sulfuric acid alumina templates by alternating current deposition, nonuniform growth of the Co nw tufts and mushrooms was obtained for the case of oxalic acid templates. We showed herein for the first time that such configurations arise from the spontaneous growth of cobalt nw groups evolving from the cobalt balls at the Al/alumina interface. Nevertheless, the uniform growth of densely packed cobalt nw arrays, up to tens of micrometers in length, was obtained via long-term direct current galvanostatic deposition at low current density using oxalic acid templates one-side coated by conducting layer. The unique point of this regime is the formation of hexagonal lattice Co nws with a preferred (100) growth direction.
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