The Divertor Tokamak Test facility (DTT) aims at demonstrating possible solutions to the power exhaust issue to pave the path to DEMO. Here we present the numerical design and optimization of a three-strap Ion Cyclotron Resonance Heating (ICRH) antenna suitable to deliver Ion Cyclotron Radio Frequency (RF) Power on DTT plasmas. The launcher operates in the frequency range 60 – 90 MHz and here has been studied and optimized by using the commercial RF simulation software CST Studio Suite. The plasma is considered as an equivalent, high permittivity, lossy dielectric. Considering the mechanical and operational severe constraints of DTT, we firstly designed an antenna flat model with the objectives to optimize the structure for coupling a power 1.5 MW to the dielectric load with a progressive phase shift of 180◦ between toroidally adjacent straps. The second part of the work regarded the design and optimization of a parametric curved antenna model in CST, which employs poloidal and toroidal curvatures suitable to better couple RF to DTT plasmas. The antenna curved model has been re-optimized in terms of coupled power and electric field values to match DTT requirements.

The INFN Laboratori Nazionali di Frascati were established in 1954 to host an electro-synchrotron, the first particle accelerator built in Italy, and since then played a crucial role in the field of nuclear and particle physics. Within this historical tradition, a workshop was organized at LNF in the framework of the Nuclear Physics Midterm Plan in Italy, an initiative of the Nuclear Physics Division of the Istituto Nazionale di Fisica Nucleare, to discuss a research program in nuclear physics in a time perspective ranging from five to ten years based on the existing facilities and on future initiatives as the EuPRAXIA project. The present report summarizes the outcome of the discussions which arose before and during the workshop, which were focused on two main topics: an extension of the physics program of the SIDDHARTA experiment, devoted to the study of the strong interactions in the strange sector through the investigation of the properties of kaonic atoms using DA Φ NE, and the development of a new research program in nuclear astrophysics to be carried out using the high-intensity lasers at LNF. The paper complements the analogue works of the Italian Laboratori Nazionali di Legnaro, Laboratori Nazionali del Sud, Laboratori Nazionali del Gran Sasso and the Laboratori Nazionali di Frascati-Detector session that described the scientific program foreseen in the next years in each of the laboratories of the “Istituto Nazionale di Fisica Nucleare” (INFN) and are summarized in a dedicated Focus Point.

Magnetized plasmas in compact traps offer a unique environment for fundamental research. PANDORA (Plasma for Astrophysics Nuclear Decay Observations and Radiation for Archeometry) is a multidisciplinary project focused on studying β decays in plasmas, using a novel facility that replicates stellar-like conditions. The project also supports applications to materials science, accelerator and ion source technologies, etc. A plasma diagnostics system based on a soft X-ray pinhole camera has been designed and implemented, with an innovative algorithm for Single-Photon Counting (SPhC) and High Dynamical Range (HDR) analysis. This enables space-resolved X-ray spectroscopy and the determination of magneto-plasma properties like local thermodynamic parameters (in terms of electron density and temperature) and confinement dynamics. This work presents results from an AI-based model in MATLAB designed to optimize the above mentioned algorithm. Using K-means clustering, events with similar features were grouped to identify those distinguishing real from spurious ones. A labeled dataset then is used to train a neural network to minimize pile-up, accelerating the recovery of high-resolution spectra and improving soft X-ray emission analysis. This contribution details the current neural network development stage and first applications to experimental data acquired during an experimental campaign carried out at the ATOMKI Laboratory.

Abstract To improve the performances of ECR Ion Sources, several approaches are possible. One proposed by INFN consists in the re-design of the plasma chamber and of its microwave injection system. In this work we propose an innovative plasma chamber named IRIS (Innovative Resonator Ion Source), whose shape is derived from the electrons last iso-density surface as the electrons move under the influence of the confining minimum-B magnetic field. Moreover, a new microwave launching system, based on a slotted waveguide that smoothly matches the cavity wall profile, is proposed. The simultaneous adoption of these two approaches increases the source performances by: a) the excitation of electromagnetic modes with a predominance of electric field along the cavity axis, unlike the standard cylindrical plasma chambers and b) a more uniform power deposition into the plasma core due to the injection waveguide radiating slot positions. The plasma chamber and its microwave injection system have been designed by using CST Studio Suite with the objective to maximize the waveguide-to-cavity microwave coupling for the modes excited inside the operational frequency interval. Particle-In-Cell simulations have confirmed the higher in-plasma energy deposition expected for IRIS compared to a conventional cylindrical cavity. By employing COMSOL Multiphysics, a combination of RF, thermal and structural simulations have also been carried out to assess the correct behaviour of the water cooling system. A full-scale structure prototype has been realized in Additive Manufacturing (AM) technique via Laser Powder Bed Fusion (LPBF) technology and post-processed via Plasma Electrolytic Polishing (PEP). It has been then experimentally characterized in terms of S-parameters (modal distribution) and on-axis electric field measurement for selected modes through the bead-pull technique. Experimental results are coherent with numerical simulations, confirming the correctness of the design and of the fabrication process.

This work introduces a novel 1D hybrid modeling approach to investigate how density fluctuations localized in the edge and Scrape-Off Layer (SOL) regions of tokamaks affect ion-cyclotron wave propagation and absorption in a relevant Divertor Tokamak Test (DTT) plasma scenario. The wave-power transmission through the edge is obtained using the Invariant Imbedding Method in the fluctuating layer, while the absorbed power fractions in the smooth core are evaluated with finite-element and Wentzel–Kramers–Brillouin based approaches. Time-independent and spatially correlated density fluctuations are generated analytically via a correlation-matrix method with prescribed root-mean-square amplitude and correlation length, and are superposed on an analytical equilibrium profile. A Monte Carlo approach is then used to sample many realizations and perform statistical analysis. The resulting edge power-transmission distribution exhibits a clearly multimodal structure, with peaks at high, low, and intermediate transmission levels. The model is fully implemented in Python and is computationally lightweight, making it suitable for fast exploratory studies without the need for high-performance computing resources, which are typical of high-fidelity modeling.

Abstract Electron Cyclotron Resonance-based charge breeding is a reliable and well-established technique to boost the charge states of radioactive ions produced in Isotope Separation Online (ISOL) Facilities. While its first applications relied on a pure experimental approach, the optimization of charge breeding has recently benefitted from numerical simulations guiding the experiments and providing insights into various steps of the process. Due to the complexity of the charge breeding process involving several steps such as the 1+ beam capture, step-wise ionization to high charge states and extraction of the high charge state ions, the experiments and simulations sometimes deviate from each other. This contribution describes the latest results of numerical simulations with the aim of focussing on the role of different plasma parameters on the overall capture efficiency, thus trying to merge in a unified description of both experimental and numerical evidences in qualitative terms. We describe the numerical approach, show that parameters like ion temperature, plasma density and potential (absolute value and profile) affect the simulated capture of the injected 1+ ions, discuss the experimental evidence corroborating the simulation results, and highlight discrepancies between experiments and simulations.

Laboratory magnetoplasmas can become an intriguing experimental environment for fundamental studies relevant to nuclear astrophysics processes. Theoretical predictions indicate that the ionization state of isotopes within the plasma can significantly alter their lifetimes, potentially due to nuclear and atomic mechanisms such as bound-state β-decay. However, only limited experimental evidence on this phenomenon has been collected. PANDORA (Plasmas for Astrophysics, Nuclear Decay Observations, and Radiation for Archaeometry) is a novel facility which proposes to investigate nuclear decays in high-energy-density plasmas mimicking some properties of stellar nucleosynthesis sites (Big Bang Nucleosynthesis, s-process nucleosynthesis, role of CosmoChronometers, etc.). This paper focuses on the case of 7Be electron capture (EC) decay into 7Li, since its in-plasma decay rate has garnered considerable attention, particularly concerning the unresolved Cosmological Lithium Problem and solar neutrino physics. Numerical simulations were conducted to assess the feasibility of this possible lifetime measurement in the plasma of PANDORA. Both the ionization and atomic excitation of the 7Be isotopes in a He buffer Electron Cyclotron Resonance (ECR) plasma within PANDORA were explored via numerical modelling in a kind of “virtual experiment” providing the expected in-plasma EC decay rate. Since the decay of 7Be provides γ-rays at 477.6 keV from the 7Li excited state, Monte-Carlo GEANT4 simulations were performed to determine the γ-detection efficiency by the HPGe detectors array of the PANDORA setup. Finally, the sensitivity of the measurement was evaluated through a virtual experimental run, starting from the simulated plasma-dependent γ-rate maps. These results indicate that laboratory ECR plasmas in compact traps provide suitable environments for β-decay studies of 7Be, with the estimated duration of experimental runs required to reach 3σ significance level being few hours, which prospectively makes PANDORA a powerful tool to investigate the decay rate under different thermodynamic conditions and related charge state distributions.

An in-depth analysis of Ion Cyclotron Resonance Heating (ICRH) absorption in the Divertor Tokamak Test (DTT) plasma has been performed over the years following the evolution of the machine parameters: i.e. magnetic 2ield, major and minor radii, etc. and in agreement with the prescription of the transport codes regarding expected kinetic pro+iles. The use of the ICRH in DTT even with plasma parameters at reduced toroidal magnetic /ield has recently reopened the analysis and modelling of the ICRH also in this context in order to evaluate whether the antenna setup (frequency range, coupled spectra etc.) is compatible with the scenario planned in the 'irst years of DTT operations. To this end, the numerical code TORIC-SSFPQL has been extensively used for a parametric analysis: minority or majority heating ("irst harmonic of Deuterium in the Hydrogen minority scenario), magnetic *ield, frequency, spectra (parallel wave number, power, etc.) in both full heating and full performance machine scenarios and also in the reduced !ield plasma scenario (B=3T, Ip=2MA). In this work the results of this extensive parametric investigation are summarized, and prescriptions are also given for the correct use of ICRH in order to maximize ion heating in all the device performances.

A simple model of coupling an electromagnetic wave in the Ion Cyclotron (IC) frequency domain with a plasma in tokamak configuration is presented and solved in a simplified Cartesian geometry. The electromagnetic field radiated by the antenna is accurately described by the CST Studio suite ® that shows the electromagnetic field radiated by the antenna but does not consider the load due to the plasma just in front of the antenna itself. The Ion Cyclotron Resonance Heating (ICRH) antenna consists of several metallic straps (accommodated in a tokamak port), on which a current flows that varies sinusoidally with time. The spectrum of the electromagnetic field radiated by the antenna acts as boundary condition for the solution of the wave equation inside the plasma. A simplified equation for the IC mode inside the plasma is derived and solved in straight Cartesian geometry by considering a simplified model of the space variation of the plasma density, temperature and magnetic field profiles. In deriving the simplified wave equation, a complex dielectric tensor has been considered by separating the Hermitian (essentially given in the cold plasma approximation) from anti-Hermitian part (temperature effects and wave absorption). This model results are relevant for the Divertor Tokamak Test facility (DTT), a new tokamak device under construction at ENEA research center in Frascati (Italy). DTT will be equipped with an ICRH system, whose construction is ongoing.

X-ray emission characterization provides valuable insights about electron cyclotron resonance (ECR) plasmas. In principle, space-resolved spectroscopic techniques can be used to reveal spatial distributions of electron density and temperature. In the PANDORA (Plasma for Astrophysics, Nuclear Decay Observation, and Radiation for Archaeometry) project framework, and within the collaboration between the Atomki and INFN-LNS laboratories, we developed a high-resolution full-field x-ray pinhole setup. This setup incorporates advanced analysis techniques for single photon counted imaging in high dynamical range mode, enabling x-ray imaging and space-resolved spectroscopy at high spatial and energy resolution (560 μm and 242 eV @ 8.1 keV, respectively). Here, we introduce an innovative technique for quantitatively evaluating the local electron density and temperature of plasma, as the first application of such a method in an ECR setup. Specifically, we examine an argon plasma heated by 200 W microwave power at 14 GHz. Our analysis includes a retrospective comparison with past x-ray data collected from other ECR ion source setups. Our findings clearly reveal the formation of a plasmoid–halo structure within the plasma chamber, characterized by a dense and hot plasma almost totally enclosed inside the ECR magnetic iso-surface (the plasmoid). This plasmoid exhibits nearly uniform distribution of electron density and temperature, with only gentle gradients of both the parameters toward its edges. Inside the halo, x-ray emission is minimal or even negligible. Notably, cusp structures correspond to magnetic branches where deconfined electrons impinge upon the plasma chamber walls and endplates. The average values of temperature and density measured inside the plasmoid are 12.44±1.84 keV and (1.66±0.15)×1017 m−3, respectively.

An overview is presented of the progress since 2021 in the construction and scientific programme preparation of the Divertor Tokamak Test (DTT) facility. Licensing for building construction has been granted at the end of 2021. Licensing for Cat. A radiologic source has been also granted in 2022. The construction of the toroidal field magnet system is progressing. The prototype of the 170 GHz gyrotron has been produced and it is now under test on the FALCON facility. The design of the vacuum vessel, the poloidal field coils and the civil infrastructures has been completed. The shape of the first DTT divertor has been agreed with EUROfusion to test different plasma and exhaust scenarios: single null, double null, X-divertor and negative triangularity plasmas. A detailed research plan is being elaborated with the involvement of the EUROfusion laboratories.

An analytical model and numerical simulations of the propagation and absorption of radio-frequency waves in hot magnetized (H-2) plasma are presented. First, an investigation of the impact of thermal effects on the dispersion relation of the waves has been conducted by expanding the hot plasma dielectric tensor to the first order in temperature. Second, starting with the realistic Ion Cyclotron Heating (ICH) antenna model designed for the Divertor Tokamak Test project, a simple 1D (1-dimensional) model of the wave propagation has been developed. The antenna's spectra have been extracted and analyzed using CST (R) , and the 1D wave propagation has been performed through MATLAB (R) .

. - Investigation of magnetised plasmas by advanced diagnostics is a relevant topic in the frame of ion sources for high-performance particle accelerators and in thermonuclear fusion research for energetic purposes. In this paper, we propose two different diagnostic techniques to provide complementary information on plasma properties: high-resolution Optical Emission Spectroscopy (OES) and Microwave Reflectometry (MR). Several OES measurements have been carried out at INFN-LNS to determine cold electron plasma density and temperature in the framework of the PANDORA project. Experimental results will be here presented together with an ongoing R&D simulation work for the MR system to be employed in the Divertor Tokamak Test (DTT) facility in view of reconstructing the 1D electron density profile accurately. An overview of the perspectives and challenges of the two diagnostic systems will be given.

In the framework of the multi-messenger astronomy, for a complete understanding of the heavy elements nucleosynthesis, investigation of the kilo- nova (KN) emission is crucial. The KN is a thermal transient signal following gravitational-wave events from the coalescence of compact objects. Modelling the KN light-curve is challenging: besides the difficulties in modelling the r-process synthesised elements, it requires several inputs, among which plasma ejecta opacity is still extremely uncertain. In this context, the PANDORA project aims at measuring, for the first time, opacities of a plasma resembling the plasma ejecta through which KN diffuses. In view of that, we present numerical estimates of argon plasma opacity perturbed by an external radiation flux under non local thermodynamic equilibrium. Simulations performed serve as demonstrator for further metallic elements, and their results underline that both thermodynamic parameters and radiation could impact on the opacity of the plasma.

The intrinsic poor loading of Ion Cyclotron (IC) plasma-facing antennas makes the use of Tuning and Matching Systems (TMSs) a necessity. The antenna plus TMS is a resonant system; in the TMS and access lines high voltages (tens of kV) must be accounted for in the unavoidable unmatched part of the feeding lines. In this work, we propose and test an innovative type of IC launcher; it is based on achieving resonance of the self-standing antenna, i.e. without the TMS. A mechanical full-metal tuning mechanism is described and demonstrated to allow wide-band operation. A systematic analysis of possible antenna topologies has led to identifying a structure that can allow good impedance matching along with compliance with maximum electric field constraints. Most of the design is carried out using a simplified plasma and a commercial analysis tool and then validated with a realistic plasma using TOPICA code.

PANDORA (Plasmas for Astrophysics Nuclear Decays Observation and Radiation for Archaeometry) is an INFN project aiming at measuring, for the first time, possible variations in in-plasma β-decay lifetimes in isotopes of astrophysical interest as a function of thermodynamical conditions of the in-laboratory controlled plasma environment. Theoretical predictions indicate that the ionization state can dramatically modify the β-decay lifetime (even of several orders of magnitude). The PANDORA experimental approach consists of confining a plasma able to mimic specific stellar-like conditions and measuring the nuclear decay lifetime as a function of plasma parameters. The β-decay events will be measured by detecting the γ-ray emitted by the daughter nuclei, using an array of 12 HPGe detectors placed around the magnetic trap. In this frame, plasma parameters have to be continuously monitored online. For this purpose, an innovative, non-invasive multi-diagnostic system, including high-resolution time- and space-resolved X-ray analysis, was developed, which will work synergically with the γ-rays detection system. In this contribution, we will describe this multi-diagnostics system with a focus on spatially resolved high-resolution X-ray spectroscopy. The latter is performed by a pin-hole X-ray camera setup operating in the 0.5–20 keV energy domain. The achieved spatial and energy resolutions are 450 µm and 230 eV at 8.1 keV, respectively. An analysis algorithm was specifically developed to obtain SPhC (Single Photon-Counted) images and local plasma emission spectrum in High-Dynamic-Range (HDR) mode. Thus, investigations of image regions where the emissivity can change by even orders of magnitude are now possible. Post-processing analysis is also able to remove readout noise, which is often observable and dominant at very low exposure times (ms). Several measurements have already been used in compact magnetic plasma traps, e.g., the ATOMKI ECRIS in Debrecen and the Flexible Plasma Trap at LNS. The main outcomes will be shortly presented. The collected data allowed for a quantitative and absolute evaluation of local emissivity, the elemental analysis, and the local evaluation of plasma density and temperature. This paper also discusses the new plasma emission models, implemented on PIC-ParticleInCell codes, which were developed to obtain powerful 3D maps of the X-rays emitted by the magnetically confined plasma. These data also support the evaluation procedure of spatially resolved plasma parameters from the experimental spectra as well as, in the near future, the development of appropriate algorithms for the tomographic reconstruction of plasma parameters in the X-ray domain. The described setups also include the most recent upgrade, consisting of the use of fast X-ray shutters with special triggering systems that will be routinely implemented to perform both space- and time-resolved spectroscopy during transient, stable, and turbulent plasma regimes (in the ms timescale).

An innovative ECR ion trap facility, called PANDORA (Plasma for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry), was designed for fundamental plasma processes and nuclear physics investigations. The overall structure consists of three subsystems: a) a large (70 cm in length, 28 cm in inner diameter) ECR plasma trap with a fully superconducting B-minimum magnetic system (Bmax = 3.0 T) and an innovative design to host detectors and diagnostic tools; b) an advanced non-invasive plasma multidiagnostics system to locally characterize the plasma thermodynamic properties; c) an array of 14 HPGe detectors. The PANDORA facility is conceived to measure, for the first time, in-plasma ss-decaying isotope rates under stellar-like conditions. The experimental approach consists in a direct correlation of plasma parameters and nuclear activity by disentangling - by means of the multidiagnostic system that will work in synergy with the.-ray array - the photons emitted by the plasma (from microwave to hard X-ray) and.-rays emitted after the isotope ss-decay. In addition to nuclear physics research, fundamental plasma physics studies can be conducted in this unconventional ion source equipped with tens of detection and diagnostic devices (RF polarimeter, optical emission spectroscopy (OES), X-ray imaging, space and time-resolved spectroscopy, RF probes, scope), with relevant implications for R&D of ion sources for accelerator physics and technology. Several studies have already been performed in downsized nowadays operating ECRIS. Stable and turbulent plasma regimes have been described quantitatively, studying the change of plasma morphology, confinement, and dynamics of losses using space resolved X-ray spectroscopy.

Metals can be injected into electron cyclotron resonance ion sources (ECRIS) via different techniques, among which resistive ovens are used to vaporize neutral materials, later captured by the energetic plasma that will step-wise ionize them, hence giving multiply charged ion beams for accelerators. Recently, PANDORA, a novel ECR plasma trap, has been conceived to perform interdisciplinary research spanning from nuclear physics to astrophysics, where inplasma high charge states of metallic species are demanded. However, a full knowledge on the vaporization method and on the coupling of neutral atoms with plasma and its overall dynamics is still not available. Simulations, hence, are of fundamental relevance to improve the overall efficiency, reduce consumption of rare expensive isotopes, and to improve the ion source performance. We present a numerical study about metallic species suitable for oven injection in ECRIS, focusing on metals diffusion, transport, and wall deposition under molecular flow regime. We studied the metal dynamics with and without plasma. Results underline the plasma role on a space-dependent conversion yield, reflecting the strongly inhomogeneous ECR plasma. The plasma and its parameters have been modelled using an established self-consistent particle-in-cell model. The numerical tool is conceived for the PANDORA plasma trap but can be extended to other ECR plasmas and traps. As test cases we studied the Cs-134 and Ca-48 radioisotopes, as metals of interest for the modern nuclear physics. A focus is given on the beta-decaying Cs-134, as an application case for PANDORA, providing quantitative estimates of the gamma-detection signal-poisoning effect by neutral metals deposition at the chamber wall.

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.

We present a new theory describing the variation of electron capture and bound-state β-decays in atomic ions and (non) local thermodynamic equilibrium ((N)LTE) plasmas. We adopt the Takahashi-Yokoi nuclear model with added corrections to first calculate the decay rate for each atomic configuration of the isotope, and then evaluate the in-plasma decay rate by combining them with the charge state distribution (CSD) consistent with plasma density and temperature. Our approach expands the thermodynamic parameter space in which in-plasma β-decays can be studied, opening the possibility to validate the model in low-density laboratory magnetoplasmas before application to stellar nucleosynthesis. The model is explained using ^7Be, and then applied to higher mass isotopes such as ^140Pr^0+,57+,58+, ^142Pm^0+,59+,60+ and ^163Dy^66+. Our model is therefore amenable to isotopes in a wide range of masses, in both single charge state or in a plasma-generated CSD.