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Hollow core microstructures powered by infrared lasers represent a new and promising area of accelerator research, where advanced concepts of electromagnetism must be used to satisfy multiple requirements. Here, we present the design of a dielectric electromagnetic band gap (EBG) mode launcher–converter for high-power coupling in dielectric laser accelerators (DLAs). The device is based on a silicon woodpile structure, and it is composed of two perpendicularly coupled hollow-core waveguides—a transverse electric (TE)-like mode waveguide (excited from laser power) and a transverse magnetic (TM)-like mode (accelerating) waveguide—in analogy with the TE10-to-TM01 waveguide mode converters of radio frequency (RF) linear accelerators (LINACs). The structure is numerically designed and optimized, showing insertion losses (IL)

This paper describes three-dimensional numerical simulations and Radio Frequency (RF) measurements of wave propagation in microwave-heated magnetized plasmas of ion sources. Full-wave solution of Maxwell's equations has been addressed through the Finite Element Method (FEM) commercial software COMSOL. Our numerical model takes into account the strongly inhomogeneous and anisotropic magnetized "cold" plasma medium. The simulations reproduce the main features of the wave-plasma interaction of the Flexible Plasma Trap (FPT) that recently came into operations at INFN-LNS. A two-pins RF probe has been ad-hoc developed and used as a plasmaimmersed antenna for measuring local wave electric fields in the FPT device. The measurements of plasma electron density and RF electric field, performed for different external magnetic field configuration, allowed a direct comparison with the assumed simulation model.

The PANDORA project aims to investigate, by a new experimental approach, the β-decays lifetimes of isotopes of nuclear astrophysics interest as a function of thermodynamic conditions of a laboratory plasma able to mimic some stellar-like conditions. A γ-ray detection system was designed by GEANT4 simulations to tag the in-plasma β-decays via the γ-rays emitted from the excited states of the daughter nuclei. The feasibility of PANDORA, in terms of significance levels, was checked by a “virtual experiment run”, also investigating the sensitivity for discriminating among different theoretical predictions.

Theoretical predictions as well as experiments performed at Storage Rings have shown that a high degree of ionization can affect the half-life of β-radionuclides. The PANDORA project aims at investigating,for the first time, beta decay rates in a plasma, simulating specific stellarlike conditions. A description of the physics motivations and the experimental setup developed to accomplish this task is given. The physics cases selected for the first experimental campaign are also presented.

At the Italian National Institute for Nuclear Physics-Southern National Laboratory (INFN-LNS), and in collaboration with the ATOMKI laboratories, an innovative multi-diagnostic system with advanced analytical methods has been designed and implemented. This is based on several detectors and techniques (Optical Emission Spectroscopy, RF systems, interfero-polarimetry, X-ray detectors), and here we focus on high-resolution, spatially resolved X-ray spectroscopy, performed by means of a X-ray pin-hole camera setup operating in the 0.5–20 keV energy domain. The diagnostic system was installed at a 14 GHz Electron Cyclotron Resonance (ECR) ion source (ATOMKI, Debrecen), enabling high-precision, X-ray, spectrally resolved imaging of ECR plasmas heated by hundreds of Watts. The achieved spatial and energy resolutions were 0.5 mm and 300 eV at 8 keV, respectively. Here, we present the innovative analysis algorithm that we properly developed to obtain Single Photon-Counted (SPhC) images providing the local plasma-emitted spectrum in a High-Dynamic-Range (HDR) mode, by distinguishing fluorescence lines of the materials of the plasma chamber (Ti, Ta) from plasma (Ar). This method allows for a quantitative characterization of warm electrons population in the plasma (and its 2D distribution), which are the most important for ionization, and to estimate local plasma density and spectral temperatures. The developed post-processing analysis is also able to remove the readout noise that is often observable at very low exposure times (msec). The setup is now being updated, including fast shutters and trigger systems to allow simultaneous space and time-resolved plasma spectroscopy during transients, stable and turbulent regimes.

A quantitative analysis of X-ray emission from an electron cyclotron resonance (ECR) plasma was performed to probe the spatial properties of electrons having energy for effective ionisation. A series of measurements were taken by INFN-LNS and ATOMKI, capturing spatially and spectrally resolved X-ray maps as well as volumetric emissions from argon plasma. Comparing the former with model generated maps (involving space-resolved phenomenological electron energy distribution function and geometrical efficiency calculated using ray-tracing Monte Carlo (MC) routine) furnished information on structural aspects of the plasma. Similarly, fitting a model composed of bremsstrahlung and fluorescence to the volumetric X-ray spectrum provided valuable insight into the density and temperature of confined and lost electrons. The latter can be fed back to existing electron kinetics models for simulating more relevant energies, consequently improving theoretical X-ray maps and establishing the method as an excellent indirect diagnostic tool for warm electrons, required for both fundamental and applied research in ECR plasmas.

The selection of the best Light Emitting Diode (LED) technologies for space application is a challenging issue, requiring a trade-off of several aspects starting from the intrinsic properties of the die. Starting from a previous evaluation of the LEDs for optocouplers by the team, the effects of proton-induced radiation damage on several types of more modern LEDs fabricated by different manufacturers and technologies are discussed in this paper. The test results have been validated by the supervising entity, according to their needs. The adopted methodology contemplated more than 150 devices, belonging to several technological options under comparison, irradiated unbiased. Electrical and electro-optical parameters were measured and analyzed by using dedicated advanced facilities and finally, the differences in output optical power emission and spectral emission and the degradation rate of the device families under comparison have been studied. Statistical analysis was performed, using a one-sided tolerance method for hardness assurance, on the LEDs’ optical power emission and spectral emission data in which the effects of different bias currents and particle fluences were investigated. Non-Ionizing Energy Loss model of the light sources was also applied in order to qualify the results. Finally, the comparative analysis clearly showed that one specific device family, i.e. R type, was the most efficient even after proton damage, with an outstanding performance if compared to all the others, and second best in relative terms, with N type was the one with the most reduced degradation dynamics. The comparative analysis allowed the device selection for the subsequent project phase, taking the obtained results into account.

In the cylindrical resonant cavities of Electron Cyclotron Resonance Ion Sources (ECRIS) microwave fields are used to generate and sustain the plasma. The design of resonant cavities and the related microwaves injection lines play a key role in the creation of intense electromagnetic fields, to generate and sustain the magnetized plasma. This paper presents an innovative geometry, as an alternative to the conventional cylindrically shaped plasma chamber, whose aim is the improvement of the microwave-to-plasma coupling, and the consequent optimization of the on axis electric field. The geometry has been numerically validated by joining COMSOL Multiphysics®, for the calculation of the electromagnetic fields and MatLab® to implement the plasma through its 3D dielectric tensor. The results are very promising and could be applied to any ECRIS.

The design of a microwave antenna sustaining a high-energy-content plasma in Electron Cyclotron Resonance Ion Sources (ECRISs) is, under many aspects, similar to the design of a conventional antenna but presenting also peculiarities because of the antenna lying in a cavity filled by an anisotropic plasma. The plasma chamber and microwave injection system design plays a critical role in the development of future ECRISs. In this paper, we present the numerical study of an unconventionally shaped plasma cavity, in which its geometry is inspired by the typical star-shaped ECR plasma, determined by the electrons trajectories as they move under the influence of the plasma-confining magnetic field. The cavity has been designed by using CST Studio Suite with the aim to maximize the on-axis electric field, thus increasing the wave-to-plasma absorption. As a second step, an innovative microwave injection system based on side-coupled slotted waveguides is presented. This new launching scheme allows an uniform power distribution inside the plasma cavity which could lead to an increase of ion source performances in terms of charge states and extracted currents when compared to the conventional axial microwave launch scheme. Finally, the use of both the “plasma-shaped” cavity and the microwave side coupled scheme could make the overall setup more compact.

Recent models for evolved low-mass stars (with M ≲ 3 M o˙), undergoing the asymptotic giant branch (AGB) phase assume that magnetic flux-tube buoyancy drives the formation of 13C reservoirs in He-rich layers. We illustrate their crucial properties, showing how the low abundance of 13C generated below the convective envelope hampers the formation of primary 14N and the ensuing synthesis of intermediate-mass nuclei, like 19F and 22Ne. In the mentioned models, their production is therefore of a purely secondary nature. Shortage of primary 22Ne has also important effects in reducing the neutron density. Another property concerns AGB winds, which are likely to preserve C-rich subcomponents, isolated by magnetic tension, even when the envelope composition is O-rich. Conditions for the formation of C-rich compounds are therefore found in stages earlier than previously envisaged. These issues, together with the uncertainties related to several nuclear physics quantities, are discussed in the light of the isotopic admixtures of s-process elements in presolar SiC grains of stellar origin, which provide important and precise constraints to the otherwise uncertain parameters. By comparing nucleosynthesis results with measured SiC data, it is argued that such a detailed series of constraints indicates the need for new measurements of weak-interaction rates in ionized plasmas, as well as of neutron-capture cross sections, especially near the N = 50 and N = 82 neutron magic numbers. Nonetheless, the peculiarity of our models allows us to achieve fits to the presolar grain data of a quality so far never obtained in previously published attempts.

The design of resonant cavities, aimed at obtaining a desired electromagnetic field configuration, must take into account the geometry and the coupling between the cavity itself and the transmission line delivering the electromagnetic power to the structure. The design issues are even more challenging when the cavity is filled with an inhomogeneous and anisotropic medium. In this paper, we present an electromagnetic analysis, carried out by multiphysics simulations with COMSOL Multiphysics® and MatLab®, of conventional (cylindrical) and unconventional geometries for resonant cavities containing magnetically confined plasmas. The study has been applied in particular to Electron Cyclotron Resonance Ion Sources, with the aim at improving their performances.

This paper presents the design of an innovative method of microwaves injection inside an Ion source plasma chamber based on slotted waveguide antennas. This microwave launching system placed along the side walls has advantages with respect to the conventional axial end-launch waveguide scheme, and its adoption could be relevant for improving the performances of Electron Cyclotron Resonance Ion Sources (ECRISs) [1]. A better power coupling and a more symmetric power distribution from the multiple radiating waveguide slots, has been obtained by the proposed design. The slotted waveguide, operating in the band [14.2;15.25] GHz exhibits a tuning range of about 7%, thanks to the launcher to cavity coupler optimization carried out with the commercial simulator CST Microwave Studio. The modal distribution coupled inside the plasma chamber by the new launching scheme has been compared with the one obtained by the classical axial launching scheme. Furthermore, a numerical validation of future electric field profile measurement through bead-pull has been performed.

The Electron Cyclotron Resonance (ECR) Charge Breeding (CB) technique consists in transforming the charge state of an input beam from 1+ to n+ to allow post-acceleration. The optimization of an ECR-CB requires a deep investigation of ion dynamics and electron heating, the latter being influenced by the microwave-to-plasma coupling mechanism. In this paper, we report the electromagnetic analysis of the microwave-to-plasma coupling of the Selective Production of Exotic Species charge breeder (SPES-CB) plasma chamber, taking into account the presence of the plasma through its dielectric tensor, performed using a self-consistent approach. In particular, the effect of two different frequencies on the plasma-wave interaction will be shown, in terms of electromagnetic properties such as plasma-absorbed power, giving numerical evidence of the frequency tuning effect.

In this paper, we present and validate a 3D full-wave numerical model for solving the wave propagation in the anisotropic magnetoplasma of Electron Cyclotron Resonance (ECR) ion sources, with the aim to analyze and design radiofrequency antennas which could produce Ion Cyclotron Resonance Heating (ICRH). Our tool is based on the coupling between COMSOL FEM solution of Maxwell equations and the MATLAB-computed non-homogeneous plasma dielectric tensor. This approach allows the evaluation of RF absorbed power by the plasma as well as the antenna input impedance which represents a crucial parameter for the design of the feeding and matching circuits usually adopted in ICRH setup. A numerical study has been performed by varying antenna geometry and plasma parameters: results are reported and cross-validated against other models.

The slowing down and capture by a plasma of externally injected 1+ ions, as a consequence of very frequent elastic Coulomb collisions, is the main mechanism involved in the charge breeding process based on electron cyclotron resonance ion sources. The Istituto Nazionale di Fisica Nucleare ion source group has been undertaking an intense activity on numerical simulations of the beam-plasma interaction, developing a code that has been proven to be very effective in reproducing several experimental results of charge breeding of light and heavy ions. This contribution will present the progress made in the development of the numerical code, focusing the attention on the latest simulations of charge breeding of Rb1+ ions employing a self-consistent plasma target model. The effect of the real plasmoid/halo structure on the capture process will be underlined, as well as the influence of different plasma excitation frequencies.

This paper reviews the main microwave diagnostic techniques and tools adopted in electron cyclotron resonance (ECR) (and others) ion source laboratories, with a special focus on techniques and instruments developed at INFN-LNS. Along with the tools used for optimization of microwave launching (power monitors, spectral analysis, and network analyzers), this paper deals, in particular, with more recent devices on-purpose developed to perform in-plasma analysis, such as absolute density measurements and density profiles retrieval. Among these, the first example of microwave interferometry for ECR compact machines (the VESPRI interferometer at INFN-LNS) will be briefly discussed, in combination with microwave polarimetric techniques based on Faraday rotation detection. More sophisticated microwave techniques are going to be designed and are now at a numerical study stage, e.g., profilometry and imaging via inverse scattering methods (this paper will offer short theoretical bases and first numerical results on 1D profilometry). In the end, the relevance about the implications and interplays of microwave techniques in multidiagnostic systems (microwave, optical, and x-ray domains) will be commented, with a special focus on time resolved microwave measurements and advanced signal processing via wavelet transform, useful for characterization of plasma instabilities.

A numerical tool for analysing spatially anisotropic electron populations in electron cyclotron resonance (ECR) plasmas has been developed, using a trial-and-error electron energy distribution function (EEDF) fitting method. The method has been tested on space-resolved warm electrons in the energy range $2-20\,\mathrm{keV}$, obtained from self-consistent simulations modelling only electron dynamics in ECR devices, but lacked real-world validation. For experimentally benchmarking the method, we attempted to numerically reproduce the experimental X-ray emission spectrum measured from an argon plasma. Results of this analysis have provided crucial information about density and temperature of warm electrons, and competing distributions of warm and hot electron components. This information can be fed back to simulation models to generate more realistic data. Subsequent application of the numerical tool as described to the improved simulation data can result in continuous EEDFs that reflect the nature of charge distributions in anisotropic ECR plasmas. These functions can be also applied to electron dependent reactions, in order to reproduce experimental results, like those concerning space-dependent K$\alpha$ emissions.

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.

Microwave imaging can provide effective means for non invasive electromagnetic diagnostics of plasma showing several advantages with respect to traditional techniques. Although microwave imaging entails solution of a full wave inverse scattering problem, it can be addressed in a less complex (but not simpler) way considering the one-dimensional inverse scattering problem for microwave imaging profilometry (MIP). In this contribution, we describe a frequency difference domain approach for MIP and provide a possible 3D full wave experimental setup in order to make a step forward application of MIP against laboratory experimental data.

A 10Be beam having intensities up to 3 enA has been accelerated at the Tandem of the Laboratori Nazionali del Sud in Catania. The used 10Be was chemically extracted from a proton irradiated graphite target used for muon production at the Paul Scherrer Institute. In order to maximise the extracted current using a minimum amount of isotope, several preparatory tests, needed to optimise the preparation of the Tandem sputter source cathodes, were performed. The acceleration tests and accelerated beam characteristics will be discussed and examples of beam use for nuclear structure investigations will be presented.

Experiments performed on Storage Rings have shown that lifetimes of beta-radionuclides can change dramatically as a function of theionization state. PANDORA (Plasmas for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry) aims at measuring, for the first time, nuclear β-decay rates in stellar-like conditions, especially for radionuclides involved in nuclear-astrophysics processes (BBN, s- processing, CosmoChronometers, Early Solar System formation). Compact magnetic plasma traps, where plasmas reach density ne~10n-1014 cm-3, and temperature Te~0.1-30 keV, are suitable for such studies. The decay rates can be measured as a function of the charge state distribution of the inplasma ions. The collaboration is now designing the plasma trap able to reach the needed plasma densities, temperatures and charge states distributions. A first list of radioisotopes, including tens of physics cases of potential interest is now available. Possible physics cases include, among the others, 2°4Tl, 63Ni, 6°Co, 171Tm, 147Pm, 85Kr, 176Lu and the pairs 187Re-187Os and 87Sr-87Rb, which play a crucial role as cosmo-clock. Physics cases are now under evaluation in terms of lifetime measurements feasibility in a plasma trap.

Magnetized plasmas in compact traps may become experimental en-vironments for the investigation of nuclear beta-decays of astrophysical inter-est. In the framework of the project PANDORA (Plasmas for Astrophysics, Nuclear Decays Observation and Radiation for Archaeometry) the research ac-tivities are devoted to demonstrate the feasibility of an experiment aiming atmeasuring lifetimes of radionuclides of astrophysical interest when changing the charge state distribution of the in-plasma ions and the other plasma param- eters such as density and temperature. This contribution describes the multidi-agnostics setup now available at INFN-LNS, which allows unprecedented in-vestigations of magnetoplasmas properties in terms of density, temperature and charge state distribution (CSD). The setup includes an interfero-polarimeter for total plasma density measurement, a multi-X-ray detectors system for X-ray spectroscopy (including time resolved spectroscopy), an X-ray pin-hole camera for high-resolution 2D space resolved spectroscopy, a two-pin plasma-chamber immersed antenna for the detection of plasma radio-self-emission, and differ- ent spectrometers for the plasma-emitted visible light characterization. The setup is also suitable for other studies of astrophysical interest, such as turbulent plasma regimes dominated by the so-called Cyclotron Maser Instability, which is a typical kinetic turbulence occurring in astrophysical objects like magnetized stars, brown dwarfs, etc. A description of recent results about plasma parame- ters characterization in quiescent and turbulent Electron Cyclotron Resonance-heated plasmas will be given.

The Advanced Ion Source for Hadrontherapy (AISHa) has been designed to generate high brightness multiply charged ion beams for hadron therapy applications. AISHa is a compact electron cyclotron resonance ion source whose hybrid magnetic system consists of a permanent Halbach-type hexapole magnet and a set of independently energized superconducting coils. This has allowed us to achieve high performances in a cost effective way. During the commissioning phase, a few criticalities have been observed and fixed in 2018/19; the improvements will be briefly described and the results of the operations with a single 18 GHz generator will be presented. Particular relevance will be given to the production of high intensity beams of oxygen, argon, and carbon, the latter having huge importance for hadron therapy applications. Perspectives for further improvements, including double frequency heating, will also be highlighted.

The Electron Cyclotron Resonance Ion Sources (ECRIS) are nowadays the most effective devices to provide relatively intense currents for highly charged ions devoted to particle accelerators for nuclear science and applications. In ECRIS, the main mechanism of microwave-to-electrons energy transfer is the Electron Cyclotron Resonance heating, when electrons gyrofrequency $\boldsymbol{f}_{\boldsymbol{ce}}=\boldsymbol{eB}/(2\boldsymbol{\pi} \boldsymbol{m}_{\boldsymbol{e}})$ equals the frequency $\boldsymbol{f}_{\boldsymbol{\mu} \boldsymbol{wave}}$ of the injected microwaves. In ECR plasmas, because of the low electron-ion collision cross-section, the ions remain cold (few eV or less). A direct mastering of the ion temperature through Ion Cyclotron Resonance Heating (ICRH) could be relevant both for improving the performances of the ECRIS as well as for fundamental Physics. In this latter case, the aim is to investigate nuclear decays as a function of the ionization state or the ion temperature. In this paper, the modeling of Radio Frequency (RF) wave-plasma interactions in the ICRH range is investigated for the first time in a compact ECR, B-minimum plasma trap. RF field computation - based on a 3D full-wave FEM-based code - is able to predict wave propagation and power absorption in a non-uniform “cold” anisotropic plasma bounded by a metallic resonator and immersed in a magnetic configuration typical of ECR ion sources. Moreover, some technological aspects and a conceptual design of the RF antenna and related systems delivering multi-kilowatts of power to the plasma ion component are discussed.

The impact of the magnetic field profile on the operations of plasma-based Electron Cyclotron Resonance Ion Sources (ECRIS) has been debated and investigated for a long time, and a summary is given by the collection of the so-called ``magnetic scaling laws'', i.e., some rules-of-thumb providing the optimal configuration of the axial and radial confining magnetic fields. Anyway, the optimal configurations have been found just looking at the output beam currents and charge states. Only recently, more advanced experiments have shown that the optimal performances are related to some ``islands" in the parameters space leading to a dense, energetic but stable plasma. A general, systematic characterization of plasma density and temperature as a function of the magnetic scaling, and for different energy domains (i.e., for cold, warm, and hot electrons) is not yet available. This paper presents a multidiagnostics characterization of a hydrogen plasma heated by microwaves at around 6.8 GHz via Electron Cyclotron Resonance, and confined in an axisymmetric simple mirror magnetic trap. Investigation of plasma response to solely the axial field profile gives the unique opportunity to decouple the effect of simple mirror field from the radial components that are, usually, provided by a hexapole. Optical emission spectroscopy, Langmuir probe, and an x-ray silicon drift detector were simultaneously used to evaluate the plasma density and temperature in different energy domains, thus exploring the electron energy distribution function from a few eV to hundreds of keV. Plasma parameters have been measured as a function of the magnetic field profile (in particular by varying the ratio ${B}_{\mathrm{min}}/{B}_{\mathrm{ECR}}$), of the microwave power and of the neutral pressure. Furthermore, for the same scaling, the relative abundances of $H$ atoms and ${H}_{2}$ have been estimated. Data show smooth trends of electron density and temperatures versus microwave power and neutral pressure, but strong and even nonlinear responses as a function of the magnetic field profile variation, allowing us to connect semiempirical scaling laws to changes in plasma parameters.

Several experiments have shown that the insertion of insulator materials within the plasma chamber may lead to a general improvement of microwave discharge ion source performances. In particular, the insertion of alumina into the chamber walls and borum nitride into extraction and injection flanges permits to increase the extracted current and the proton fraction and leads to a general decrease in the beam ripple. These beneficial effects have been usually explained by considering the secondary electron emission of insulators hit by plasma electrons. This paper tries to illustrate that these effects can be explained by taking into account the modification of the diffusion regime induced by the insulator materials. This approach will be used to comment on the results obtained with the versatile ion source by changing the wall conditions.

The research of magnetically confined plasmas with high energy content is nowadays an important branch of the plasma physics with several options considering the chosen technics. One of the ways is the detection of photons emitted by the plasma itself. A new experimental setup was built in the ECR Laboratory of Atomki (Debrecen, Hungary) to detect in 2D the dense EM-radiation emitted by the ECR-plasma. The main elements of the setup are: an ECR ion source (as plasma source, operating at 13.6–14.6 GHz RF pumping frequency) and a pinhole X-ray camera (operating in the 500 eV–20 keV energy domain). An innovative lead collimator system was designed and built between the plasma and the camera. As a result, it has been possible to acquire X-ray pictures up to 200 W total incident RF-power. This value represents the highest operative RF power for which X-ray imaging has been acquired in the field of ECR Ion Sources and ECR compact traps. A new treatment for the noise reduction was applied to study plasma morphology. The new setup gives opportunity not just to study energetic stable plasmas, but even plasma turbulences and instabilities.

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 ${\rm e}\mu \hbox{A}$ of ${\rm U}^{33+}{\rm o}\ {\rm Xe}^{34+}$ ). 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.

This work presents the X-ray characterization of the plasma generated in simple mirror axis symmetric trap as a function of magnetic field profile. A Si-Pin detector has been used to characterize warm electron population either in axial than in radial direction at two different operating frequencies: 4.1 GHz and 6.8 GHz. Moreover, the hot electrons emitted by axial direction has been measured by means of a HyperPure Germanium (HpGe) detector. Results show that X-ray emission is not homogenous and homogeneity and temperature depends strongly on the magnetic field profile., Proceedings of the 23th Int. Workshop on ECR Ion Sources, ECRIS2018, Catania, Italy

Time resolved characterization of plasma X-ray emission represents an innovative technique to characterize non-equilibrium phases in Electron Cyclotron Resonance Ion Sources (ECRIS). Indeed, although ECRIS plasmas are usually in dynamical equilibrium, many relevant phenomena are characterized by fast transients and require a dedicated diagnostics to be fully investigated. In particular, time resolved diagnostics can be applied to characterize the X ray emission during the plasma turn on and off and during the turbulence phenomena induced by Cyclotron-Maser instability. This paper presents the experimental set-up used during the last campaign at measurement carried out at the IstitutoNazionale FisicaNucleare-LaboratoriNazionali del Sud (INFN-LNS), together with the main achieved results. Particular relevance will be given to the characterization of the afterglow phase, which highlighted the existence of two electron populations characterized by different mean lifetime. Evidences of X-ray bursts emission in the afterglow phase, compatible with Cyclotron Maser instability, will be also shown. c 2019 IOP Publishing Ltd and Sissa Medialab.

All-dielectric electromagnetic band gap (EBG) waveguides structures promise significant improvement of accelerating gradient of laser-driven acceleration with the potential to miniaturize the accelerator itself. In this work we study photonic crystal structures designed for acceleration of relativistic electrons. We explore the performance of the all-dielectric EBG accelerating waveguide structures thanks to full wave electromagnetic simulations of couplers and accelerating waveguides. The characteristic interaction impedance, accelerating gradient and all the key parameters that are typically used to characterize linear accelerators are evaluated and used to compare the properties of the accelerating mode field distribution in different geometries., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Since 2012, the INFN ion source group has been undertaking an intense activity on numerical modelling of magnetically confined plasmas, presently carried out in the framework of the PANDORA project. The aim is the development of a predictive tool for the design of Electron Cyclotron Resonance (ECR) Ion Sources or Traps and ECR-based Charge Breeders, able to determine spatial density and energy distributions for both electrons and ions. The work mainly concerns the study of two aspects: on one hand, the interaction of an ion beam with a magnetized plasma; on the other hand, the microwave-to-plasma coupling, including the 3D plasma electrons dynamics in the confinement magnetic field and intra-particles collisions. This contribution describes the state-of-the-art of the work on both the fronts: an overview of the beam-plasma interaction, showing the latest results about the ECR-plasma density fine structure, as well as electron spatial temperature distribution will be shown., Proceedings of the 23th Int. Workshop on ECR Ion Sources, ECRIS2018, Catania, Italy

Microwave-to-plasma coupling in ECRIS has been based on the classic scheme of waveguide-to-cylindrical plasma cavity matching. Optimization has been often obtained by empirical adjustments leading to an oversimplified model, obtaining however satisfying performances. In order to overcome the ECR-heating paradigm, on-purpose design of launchers' setup adequate diagnostics have to be developed. This paper describes three-dimensional numerical simulations and Radio Frequency (RF) measurements of wave propagation in the microwave-heated magnetized plasmas of ion sources. Moreover, driven by an increasing demand of high frequency ECR ion sources, innovative ideas for the geometry for both the plasma chamber and the related RF launching system - in a plasma microwave absorption-oriented scenario are presented. Finally, the design of optimized launchers enabling single-pass power deposition, not a'ected by cavity walls effects, are described., Proceedings of the 23th Int. Workshop on ECR Ion Sources, ECRIS2018, Catania, Italy