STSM-accomplished

A01 

Grantee name: Katarzyna Batani

Title: Participation in experiment on enhanced alpha-particle generation with external, laser generated magnetic fields
Start and end date: 15/02/2023 to 01/03/2023

Recently (February 2023) Dr. Katarzyna Batani (IPPLM) has been granted STSM mission by COST/PROBONO Action at GEKKO/LFEX laser systems in Japan. The goal of the experimental campaign at LFEX/GEKKO laser installation (Osaka, Japan) has been a deeper understanding of the mechanism of proton-boron fusion in laser-plasmas and, in particular, studying the effects of strong magnetic fields on alpha-generation. The LFEX beam has been the driver of protons producing pB fusion reactions within the different boron-compounds targets and the Gekko beams have been used to produce a magnetic field using the coil-target configuration. The successful performance of LFEX/GEKKO installation allowed to obtain interesting data, which are presently under analysis.

A02&A03&A06

Grantee name: Vasiliki Kantarelou

Title: Laser-driven Ion Sources for Applications
Start and end date: 06/03/2023 to 17/03/2023

CR-39 detectors were used in order to measure the number and the energy of the generated alpha particles from proton boron interaction. During the experiment, different targets were used such as B, BN, B4C and SiCa, a reference shot was also been made using pure Al target. The detectors were placed at three different angles with respect to the laser target interaction.The preliminary analysis that was made at CLPU showed the detection of alpha particles; further analysis on the rest of the detectors used in the experiment will be accomplished at University of Bordeaux and at the ELI Beamlines Facilities.

Grantee name: SINGAPPULI DILUKA

Title: Preparation of an experiment on Proton-Boron fusion at CLPU (Spain)
Start and end date: 05/03/2023 to 18/03/2023

The short visit realized within COST support allowed us to study the proton-boron fusion and the use of the HPGe diagnostic present at CLPU facility. The analysis of the data collected by the other diagnostics (TOF, CR39, TP) will provide us a better understanding of the alpha particles and alpha-calcium reactions and the productions of radioisotopes

Grantee name: Howel LARREUR

Title: Preparation of an experiment on Proton-Boron fusion at CLPU (Spain)
Start and end date: 05/03/2023 to 18/03/2023

The experiment was well done: currently, we have no knowledge of a mistake that could introduce an error in our results. Preliminary results show lower amount of protons (3 orders of magnitude) than in similar experiments done on more powerful lasers (ELFEX, PETAL). Further data analysis, especially about alpha particles in CR39 diagnostic, is required before any conclusion can be made, and thus before any follow-up activity can be decided.

A04

Grantee name: Massimiliano Scisciò

Title: Collaborative research activity on laser-driven p-11B fusion reaction at high repetition rate
Start and end date: 06/03/2023 – 11/03/2023

The Time-of-Flight (ToF) diagnostics that were provided by ENEA for the experimental activities at CLPU, were successfully implemented and yielded good measurements already in the first days of test shots. The energies of laser-accelerated protons that were measured are consistent with what is typically obtained on the Vega III laser (i.e. >10 MeV).
The preliminary analysis on the retrieved data that was performed on-site will be followed up in the coming weeks with a more detailed study. Particular attention will be given to the measurements that regard the experimental configuration with a pitcher-catcher scheme: in this case, the goal is to detect with the ToF detectors the p-11B fusion products (i.e. alpha particles). This measurement is particularly challenging, due to the extremely low flux of particles emitted from the secondary target. The test shots performed during the first days led to extensive discussions on how to optimize/improve the experimental setup (e.g. by modifying the filter on the ToF diagnostics and varying their distance to the secondary target) and attempt to improve the strength of the signature signal of alpha particles.
Implementing this type of diagnostic allowed general discussions – particularly useful for future campaigns that will be conducted within the framework of this COST action - on the suitability of semiconductor-based ToF detectors for the detection of p-11B fusion products generated on high-repetition, low energy (in this case, about 25 J) lasers. On this class of facility, where the used repetition rate was >1 shot/min, these detectors showed to be very useful for characterizing the laser-accelerated particle beam that is used for triggering the p-11B reactions, due to their ability to yield real-time measurements. Regarding the detection of the fusion reaction products, the flux of particles is extremely low: the follow up analysis will tell how in this campaign - and in future campaigns on similar high-repetition laser facilities - diamond-based ToF detectors can be used as complimentary diagnostic (in combination with passive detectors, such as CR39, capable of accumulating signal over multiple laser shots) aiming at revealing alpha particles from p-11B reactions.

The experimental activities took place at the Vega III laser facility of the CLPU laboratories in Salamanca. In the pictures, the target area bunker of Vega III and the control room.

A05

Grantee name: Francesco Filippi

Title: Collaborative research activity on laser-driven p-11B fusion reaction at high repetition rate
Start and end date: 07/03/2023 to 18/03/2023

The Time of Flight (ToF) diagnostics, provided by ENEA, were successfully implemented and used during the experimental campaign. The experiment investigated different configurations. Among them, we investigated the so-called pitcher-catcher scheme in which the laser impinges onto a primary “pitcher” target with the goal to produce protons which will hit the secondary “catcher” target, which absorb protons producing fusion reactions. The goal of the ToF diagnostic was to measure the energy spectra of the particles accelerated by the laser-pitcher interaction and the alpha particles produced by the p-11B fusion reaction in the catcher. This last task was particularly challenging due to the low rate of the produced particles and the wide angle in which they are emitted.

As expected, ToF diagnostics gave a real time feedback of the laser-accelerated particles from the first days of the campaign. The energies of laser-accelerated protons that were measured are consistent with what is typically obtained on the Vega III laser. Preliminary analysis of the acquired data was obtained on-site with an analysis routine which was optimized during the experimental activity. This allowed to have fruitful discussions with the group about the optimization and improvement of the experimental setup (e.g. by modifying the filters in front of the ToF, varying the position of diagnostics to improve the signal strength, varying the catcher position etc.). As well, we discussed the possible improvements in the data analysis and the further implementation and experimental activities to be performed in the future in the framework of the COST activity.

In the follow-up of the experiment, the data acquired will be further analyzed and the analysis routine will be integrated to give more accurate results. ToF data will be also compared with results obtained by other diagnostics, to give a deeper understanding of the physical processes involved into the experiment. Particular attention will be devoted to the results obtained by the CR39, placed in different positions inside the vacuum chamber and exposed to the fusion products emitted by the catcher, and to the Thompson parabola placed in front of the pitcher.

ToF detectors showed to be very useful for real-time characterization the laser-accelerated particle beam that is used for triggering the p-11B reactions. Regarding the detection of the fusion reaction products, the flux of particles is extremely low and the data analysis is still ongoing. Further analysis will confirm if diamond-based ToF detectors can be used also as complementary diagnostic, in combination with other detectors, for the identification of the fusion produced alpha-particles.

The experimental activities took place at the Vega III laser facility of the CLPU laboratories in Salamanca. In the pictures, the target area bunker of Vega III.

A07

Grantee name: Mattia Cipriani

Title: Collaborative research activity on laser-driven p-11B fusion reaction at high repetition rate
Start and end date: 12/03/2023 – 18/03/2023

The Time-of-Flight (ToF) diamond detectors that were provided by ENEA for the experimental activities at CLPU, were successfully implemented and yielded good measurements throughout the campaign.The energies of laser-accelerated protons that were measured are consistent with what is typically obtained on the Vega III laser and were consistent with ones measured by a Thomson spectrometer placed in proximity of the diamonds.

A preliminary analysis was made for each shot on-site, to measure the energy of the accelerated protons to give a feedback in optimizing the laser-matter interaction parameters. In the coming weeks, a detailed analysis of the results will be performed, with the aim of finding any signature of the presence of alpha particles produced in the pitcher-catcher scheme. This is a challenging task, due to the low expected flux of these particles reaching the detector. During the second week, discussions developed on how to optimize the amplitude of the signal reaching the detectors, especially the one whose line of sight was along the direction of the production of alpha particles from the catcher material. The ideas developed during these discussions will be particularly useful when planning future campaigns in the framework of this COST action.

The use of these detectors in this campaign gave many information on how to improve the effectiveness of these ToF diagnostics. In particular, the detectors proved to be very reliable for the characterization of accelerated protons. With the use of an optimized version of the software used in this campaign, it will be possible to acquire data on facilities with a repetition rate higher than 1 shot/minute, thus accumulating large statistics in a short time. This campaign will also indicate to which extent diamond-based ToF detectors are suited for the detection of the very low flux of alpha particles produced by the fusion reactions, in combination with the typical passive diagnostics, such as CR39 detectors, which can in turn accumulate the fusion products over a large number of shots. The data collected and the results of the analysis will also contribute to a more efficient design of the upcoming campaigns on similar highrepetition rate facilities in the framework of this COST action.

The experimental activities took place at the Vega III laser facility of the CLPU laboratories in Salamanca. In the pictures, Mattia Cipriani working in the interaction chamber of Vega III.

A08

Grantee name: Nicolina Pop

Title: Dissociative recombination and vibrational transitions of BF+ by electron collisions
Start and end date: 7/05/2023 to 14/05/2023

Direct STSM achievement is devoted to extend the study of dissociative recombination, vibrational excitation and vibrational de-excitation of BF+ based on the multichannel quantum defect theory. The data obtained for Maxwell rate coefficients are relevant for different communities of applied physics and engineering. Part of these data, will serve to the interpretation – and often to the calibration - of the experimental results, giving a deeper insight into the understanding of the mechanisms and interactions governing the relevant elementary processes. While this will be generally the case for ground or very weakly-excited states and on limited ranges of energy, all these imposed by the experimental constraints, our computations are extended to excited states and broad ranges of energy. The objectives of the COST action PROBONO are achieved involving an inter-disciplinary collaboration across the institutions and countries having similar interests and complementary capabilities in plasma physics.

As a follow-up activity, we plan to investigate the electron induced elementary processes involving BF3+ which has a key role in the plasma kinetics. We plan to extend the previous study on the DR of BF+ to higher collision energies making use of the molecular data calculated there.

First photo: In front of the host Institute for Nuclear Research (ATOMKI), Debrecen, Hungary.

Second photo: Working with Zsolt MEZEI, Head of the the Quantum Physics Group Institute for Nuclear Research (ATOMKI), with expertise in the electron-cation collision processes, led to the importance of the extension of our previous study on dissociative recombination, vibrational excitation and vibrational de-excitation of BF+. We analyze the potential energy curves (PECs), the coupling and quantum defects obtained.

A09

Grantee name: Marco Tosca

Title: Production of nanostructured regular patterns targets using stepper lithography and spin coating
Start and end date: 23/05/2023 to 12/06/2023

The fabricated structures exceeded the initial plan by incorporating additional dimensions and features. In addition to the 1 μm period silicon (Si) patterns, we also introduced patterns with dimensions of 1.2 μm, 1.5 μm, and 2 μm. Furthermore, nano-holes were developed within the Si, posing a greater challenge in terms of dimensions: 0.5 μm, 0.8 μm, 1.0 μm, 1.5 μm, and 2 μm. All these structures had a depth of 2 μm.

The upcoming steps involve applying an anti-stitching layer and spin coating polyethylene (PE) to replicate the negative size of the Si structures onto the PE. Additionally, boron magnetron deposition will be carried out at Charles University, and laser-driven pB fusion experiments are planned for the next experimental campaign.

As a result of this collaboration, we anticipate the publication of an article once the outcomes of the pB fusion experiments are obtained.

A10

Grantee name: Lucas Volpe

Title: laser-driven ion beam metrology for Stopping power measurement in WDM
Start and end date: 28/05/2023 to 25/06/2023

The main aim of the STSM was to participate to the first preparation weeks of the experimental campaign.This goal was successfully done and, as stated above, all the preliminary steps were reached.

Discussions were done between all the partners also for the preparation of a second proposal that is already accepted from the 5th cycle of LaserNetUS and which main goal is to advance in the characterization of the proton spatial properties by using special hemisphere bent targets. The main diagnostic will be done by coupling the proton spectrometer with K alpha x-ray imaging of the fast electrons as well as ToF techniques.

Improvement of proton beam flux will be helpful for several applications among which the enhancement of alpha particle production via secondary HB11 reaction. With respect to this a possible improvement can be predicted concerning the previous experimental activity performed by part of the members of the group last year by using the VEGA PW system at CLPU where alpha particle where investigated.

The advance of the current experiment and the establishment of a structured and long-term experimental activity in EU and USA is the main results of this STSM. The coordination of long-term scientific activity for ion beam acceleration and optimization is now defined with the main actors CLPU, PPPL and CSU in collaboration with scientist from CELIA from France, ENEA from Italy, GSI from Germany, LLNL and University of California San Diego in California, Los Alamos new Mexico, University of Alberta Canada, University of Gran Canaries.

A11

Grantee name: Dr. Donaldi Mancelli

Title: Laser-driven proton-boron fusion and the future collaboration between CELIA and HMU-IPPL
Start and end date: 05/06/2023 to 16/06/2023

During my STSM visit at the CELIA laboratory, I collaborated with Prof. Dimitri Batani's experimental group, particularly in proton-boron fusion studies. Our focus was on analysing recent experimental results concerning equation of state (EOS) studies of boron samples. One major accomplishment was the in-depth analysis of experimental data obtained from two different target designs using time resolved VISAR and SOP. This analysis provided valuable insights into the EOS properties of boron-rich target samples, enhancing our understanding of boron's behaviour under extreme conditions. To complement the experimental findings, we conducted radiative hydrodynamic simulations using the MULTI 1D code. These simulations played a crucial role in assisting our analysis of the experimental data, providing additional insights into the underlying physical processes, and facilitating a better interpretation of the results. These findings contribute to the advancement of plasma physics research and have implications for fusion energy and related technologies. Overall, the collaborative STSM visit to the CELIA laboratory, allowed us deepened our understanding of boron's EOS properties. These achievements contribute to the ongoing progress in plasma physics and lay the foundation for future developments in fusion energy research and on EOS studies. As a follow up activity, we have been granted laser beam time at two large scale laser facilities for collaborative experimental studies at (PALS ASTERIX and ELI beams in Prague during September 2023).

A12-13-14

Grantee name: Pierluigi Andreoli
Grantee name: Massimiliano Scisciò

Title: Research on high-power-laser generated currents and electromagnetic fields for applications in laser-driven p-¹¹B fusion schemes
Start and end date: 11/06/2023 – 16&17/06/2023

The electromagnetic field probes that were provided by ENEA for the experimental activities at PALS, were successfully implemented and yielded good measurements already in the first days of test shots. The conductive probes (Ddot, SWB and HORN antennas) are well-known devices, with which we have significant experience with, were immediately optimized. The optimization of electro-optical probes, novel custom-made tools for this type of experiment, delivered good initial results and will be further optimized in the following part of the campaign. The amplitude of the generated E-fields, in the range of multiple tens of kV/m, that were measured are consistent with what is typically obtained on the PALS laser and are compatible with the intensity of the measured laser-driven discharge currents, in the kA order. The preliminary analysis on the retrieved data that was performed on-site will be followed up in the coming weeks with a more detailed study. Particular attention will be given to the measurements performed with electro-optical probes. This novel diagnostics, can potentially deliver very precise information about the generated em fields (representing an improvement, compared to classical conductive probes), which are crucial for the implementation of laser-driven discharge currents and magnetic fields in nuclear fusion experiments, including laser-driven p-¹¹B fusion. These measurement are particularly challenging, due to the low sensitivity of EO probes that are, hence, heavily affected by background noise.

The data obtained with the set of ENEA diagnostics will be then compared with the results yielded by the diagnostics of other participant groups for a complete characterization of the laser-generated em fields and currents. Moreover, the test shots performed during the first days led to extensive discussions on how to optimize/improve the experimental setup: the already installed probes (conductive and dielectric) will be completed by the crystals for direct measurements of the discharge currents. Cross-corelating the data from these different diagnostics will proved crucial information on the suitability of the magnetic fields and currents generated at the PALS facility for potential future experiments on inertial confinement fusion with magnetized plasmas (MagICF), including borated plasmas for p-¹¹B fusion reactions.  

The participation to this experiment also allowed extensive general discussions – particularly useful for future campaigns that will be conducted within the framework of this COST action - on the suitability of laser-driven em fields for improved ICF experiments, also considering schemes that exploit the p-¹¹B reaction. A fruitful exchange of expertise was possible during the experimental activities: the ENEA participants provided a deep know-how concerning the revelation of the laser-driven em fields, which was complimentary to the expertise of other groups on techniques for the direct measurement of laser-driven discharge currents. We discussed the importance of accurate measurements of the generated em fields and currents, in order to understand the necessary parameters of laser-matter interaction that are required for experiments of magnetized inertial confinement fusion, also in the case of borated targets. Hence, developing accurate diagnostic tools and techniques for measuring the produced fields and currents, especially in the case of multi-hundred Joule laser systems, is a challenge that is tackled here. The campaign at the PALS laser (up to 700 J per pulse) represented an opportunity for the testing of these tools/techniques that, in future, can be implemented in MagICF experiments on similar facilities, also exploiting the p-¹¹B fusion reaction and fields related to the COST Action.

Grantee name: Fabrizio Consoli

Title: Collaborative research activity on laser-driven intense magnetic fields for application to p-11B laser-triggered fusion schemes
Start and end date: 11/06/2023 to 14/06/2023

The STSM activities were related to the laser-matter interaction experiment with the PALS laser in Prague. The experiment is now still running and the STSM was highly successful in the experiment organization and discussion of the preparation and outcomes. Moreover, the days spent in the PALS laboratory were important to enable the continuation for the STSM applicant of the coordination and management of the ENEA group participating to the experiment remotely for the following experimental weeks.

The currents we are studying in the experiment are in the kA level and are very promising for the generation of intense transient magnetic fields to be used in several applications. Two main uses of these intense fields are:
1) for laser-driven high-brightness alpha-particle sources based on laser-triggered p-11B nuclear reactions in high-repetition-rate schemes, as an alternative compact solution to standard alpha-particle sources used to produce medical radioisotopes
2) for experiments of inertial confinement fusion with p-11B fuel, both within the COST Action.

The achieved outputs from the STSM regards both the Research Coordination and the Capacity Building objectives, and not only. The STSM allowed the applicant to meet other researchers from other institutions participating in the Action, making a favourable ground for the transfer of knowledge about diagnostics specific for this experiment and for discussions about the physics behind the processes, useful to improve the produced fields, and then the use of the generated magnetic fields to p-11B advanced schemes of the COST action. The STSM allowed the scientific discussions with other participating groups about also the exploitation of potential results for the purposes of the Cost Action and the new potential developments of researches related to the COST Action

The experimental activities took place at the PALS laser facility in Prague. In the pictures, the team (the applicant is the second from the left, in both pictures) in target area of the Asterix laser, present at PALS. Among the participants, scientist from various foreign institutions and local staff from PALS, together with the host person Dr. Jakub Cikhardt, the fifth from the left on the top picture and the first on the right in the bottom picture.

The experimental activities took place at the PALS laser facility in Prague. In the two first pictures, the team in target area of the Asterix laser, present at PALS. 
In 1st picture:P. Andreoli (1st), F. Consoli (2nd), M. Scisciò (4th)
In 2nd picture:, F. Consoli (2nd), P. Andreoli (3rd), M. Scisciò (4th)
Among the participants, scientist from various foreign institutions and local staff from PALS, together with the host person Dr. Jakub Cikhardt, the 5th from the left on the first picture and the 1st on the right in the second picture
In 3rd picture: the data acquisition room where the used oscilloscopes where placed during the shots.

A15

Grantee name: Sahar Arjmand

Title: Development/optimization of advanced plasma diagnostics technique for laser-driven Proton-Boron experiments
Start and end date: 13/06/2023 to 13/07/2023

During the Short-Term Scientific Mission (STSM), we conducted a series of activities and preliminary work to study the development of plasma diagnostic techniques adapted to Proton-Boron fusion
experiments. We were also taking the steps to design a possible experiment at the CELIA laboratory using the recently upgraded ECLIPSE laser, and designed a preliminary experimental setup, including in particular the generation of the proton beam which will be used to trigger proton-boron fusion reactions.

Overall, our efforts in designing plasma diagnostic techniques for Proton-Boron fusion experiments, as well as the set-up of a possible future experiment on Eclipse, have significantly advanced my
understanding of plasma behavior, fusion reaction dynamics, and alpha particle production. The planned follow-up activities will build upon these achievements, paving the way for improved plasma diagnostics and further contributing to the development of fusion energy technologies.

I plan to continue the collaboration with the group at CELIA and to continue to refine the diagnostics techniques, incorporating any insights gained from the experimental data and comparisons with
theoretical models. Finally doting my stay, I started to write some articles in collaboration with my host, Prof. Dimitri Batani,on the topics of time resolved measurements of temperature in plasmas by analysing the emission spectra of elements like hydrogen, oxygen, nitrogen and boron.

Photos of the experimental room for ECLIPSE experiments at the CELIA Laboratory and with my host, Prof. Dimitri Batani. 

A17

Grantee name: Valeriia Istokskaia

Title: Diagnostics of particles and radiation produced in laser-plasma interaction and data analyses
Start and end date: 24/06/2023 to 08/07/20223

During the research stay, I performed additional data analyses of alpha particles and X/gamma rays generated in laser-plasma interaction in recent experiments.  Also, we had a number of discussions and seminars with colleagues from CELIA with the purpose to exchange knowledge and experience on diagnostic techniques, signal reconstruction methods, and discuss possible improvements and new ideas. Specifically, the main points of reciprocal interest constituted CR39 nuclear track detector for measuring alpha particles generated during fusion reactions initiated by laser-plasma interaction, and stack detectors for measuring bremsstrahlung X-rays generated by laser-accelerated electrons passing through matter. I presented the related research performed at the ELIMAIA team from the ELI Beamlines center, focusing on details about CR39 preparation, position, measurements, and analyses technique. At the same time, I was actively participating in presentations on the recent experimental activities and measurements given by the colleagues from CELIA and learnt about their approach for CR39 measurements and other topics (e.g. interferometry and targetry methods). Moreover, we had fruitful discussion on stack detectors for bremsstrahlung and the corresponding temperature unfolding method. I was presenting and describing in detail the setup and results we currently use at ELI BL, which lies in online scintillator based stack read out with a camera. At CELIA, a differential filter stack is available which uses a similar method for signal reconstruction and, as was found out, encounters similar obstacles during the analyses. We also discussed the scintillator detectors designed for proton measurements and alternatives for CR39 detection from recent publications. Additionally, I visited the CELIA lab and leant about the equipment and activities that can be carried on there. Finally yet importantly, I also met a lot of researchers from the same field

In general, this research stay helped to expand the CELIA-ELI Beamlines scientific network and established strong contacts for possible future collaborations. The discussions, comparison, and knowledge exchange on X-rays (bremsstrahlung) and alpha particles diagnostics enriched both sides and caused ideas planned to be checked in future. Specifically, about the signal reconstruction techniques and detectors setup. For example, we planned to collaborate during the next experiment at ELI BL using the L4n laser which is scheduled for November. Also, we agreed to meet at the Proton-Boron fusion workshop for the follow-up of the activities.

A18

Grantee name: Milan Dimitrijevic

Title: STARK BROADENING OF N VI SPECTRAL LINES
Start and end date: 27/06/2023 to 16/07/2023

As the main result, we obtained Stark broadening parameters, FWHM (full widths at half intensity maximum) and shifts, for 33 N VI spectral lines in 15 multiplets, for broadening by collisions with electrons, protons, alpha particles, B III, B IV, B V and B VI ions, using semiclassical perturbation theory. Calculations have been performed for a grid of temperatures and densities of perturbing particles.The results of the research proposed for this STSM contribute to the following working groups of CA21128:

WG2: Experiments: Proton boron and Towards the practical realization of compact laser-driven α-particle sources. Namely, profiles of N VI spectral lines may be useful to design and optimize experiments, and analyze results, since the profiles enter in the calculation of absorption coefficient which is important for the modelling and investigation of laser produced plasma. Also, line profiles are useful for the spectral analysis and diagnostics of plasma in proton-boron fusion experiments.

WG3: Modelisation including development and optimization of numerical simulations. For modelisation and optimization, data on line profiles broadened by collisions with various charged particles are also of interest, particularly since line profiles enter in the calculations of absorption coefficient and other quantities important for better understanding of proton-boron plasma. WG4: Development / optimization of advanced diagnostics for proton boron experiments. Since this WG addresses the “Challenge on development of Novel Diagnostics”, N VI spectral line profiles may be particularly interesting since such data enable plasma diagnostics by spectroscopic method.

WG5: Targetry: development and detailed characterization of proton-boron targets. The obtained resuts are of interest for boron-nitride target. 

The results obtained during this STSM will be presented in one or two articles and on a couple of Conferences. They will be also implemented in the STARK-B database, which is a part of VAMDC - Virtual Atomic and molecular data center. We will continue our collaboration trying to provide the missing data for line profiles broadened by collisions with charged particles, especially by collisions with various boron ions.

Milan Dimitrijević and Magdalena Christova in front of the Technical University in Sofia.

A19

Grantee name: Tzveta Apostolova

Title: Characterization of wide band gap materials after the excitation with high average power ultrafast laser pulses and secondary sources.
Start and end date: 09/07/2023 to 22/07/2023

Goal of the visit:
The use of very high average power laser systems is key for the application of many secondary sources. Assoc. Prof. Apostolova is targeting the use of the fiber laser technology developed by Active Fiber Systems (spin off of the Fraunhofer IOF) in Jena, which can deliver very high average power (up to 500W), for her research program in Bulgaria. This very high average power technology was recently implemented at ELI-ALPS at the level of 1mJ (100 W of average power). An application by Assoc. Prof. Apostolava group and collaborators to the second ERIC call for user has been selected to perform preliminary experiments at ALPS to assess the high average ultrafast laser technology.
The general goal of the Short-Term Scientific Mission was to assess the potential of the 100 kHz technology developed by AFS, with the possibility to generate up to 5 mJ-8 mJ level with ultrashort and near single cycle pulse (7 fs), for benchmarking theoretical studies on high harmonic generation in semiconductors realized by the applicant.

The immediate results from the STSM:
The discussions have been extremely useful to shape preliminary milestones and steps to assess how the potential of the 100 kHz technology developed by AFS at the 5 mJ-8 mJ level with ultrashort (30 fs) and near single cycle pulse (7 fs). These laser systems can be applied for benchmarking theoretical studies of energy deposition, optical breakdown and high harmonic generation in semiconductors conducted by the applicant, with a strong synergy between calculations and experiments.

Two experimental campaigns of two weeks each (total of 4 weeks) beam time were granted to the applicant at ELI-ALPS on a high average power system. Inside this experimental beam time, Assoc. Prof. Apostolova’s group and collaborators aim to test the potential of the technology in the mid-IR range (wavelength of 3 μm, energy 150 μJ, pulse duration 40 fs and repetition rate 100 kHz). Possible strategies for the experimental campaign at ALPS were outlined together with the hosts of the STSM and discussions addressed various important points as the beam focusing on a solid target with a fluence between 0.1 and 10 J/cm2, polarization on target, pulse duration range and various diagnostics needed for optical breakdown measurements.

The relevancy and relationship with Proton-Boron Fusion of the proposed Short Term scientific Mission:
On a short term, we aim to develop high repetition rate (high average power) diagnostics (VUV but also X-rays) for material characterization (including the characterization/imaging with very high resolution and very short acquisition time of targets appropriate for Proton Boron Fusion). This aspect fits in the work package WP3.

A20

Grantee name: Dimitri Batani

Title: Collaboration
Start and end date: 18/07/2023 to 22/07/2023

I visited Milano Politecnico from 18 to 22 July 2023 in order to meet Prof. Matteo Passoni and his team. The goal of the visit was to discuss future collaboration in the field of proton boron nuclear fusion and the study of the equation of state of boron and boron compounds in extreme conditions.In particular, the group led by Passoni has developed several techniques to realize foam targets and boron deposition, which can be used in laser-plasma experiments dedicated to proton born fusion on one side, and in experiments for the determination of the equation of state of boron and boron compound in the Megabar pressure range by using laser-driven shock waves. I have visited their laboratories, including different deposition techniques (ns laser, fs laser, plasma sputtering) and discussed about how they can be used for realizing targets for our experiments.

We are also discussed the latest developments in the field of laser-driven proton boron fusion. In this context I delivered a seminar on the last advancements in inertial confinement fusion for energy, following the recent breakthrough obtained at the National ignition Facility in the U.S., and I also included the perspectives of laser driven proton-boron fusion

There have been multiple outcomes from the visit:

1) Concerning equation of state experiments, we have discussed the possibility of realising targets using pure born. This seems quite difficult at the moment since the deposition of boron layers with sufficient uniformity and thickness seems to require times which are too long. However, there were some ideas on how it could be possible to improve the surface quality. Instead, deposition of boron compounds (boron nitride and boron carbides in particular) seems to be easier. We also discussed about the possibility of studying pure HB materials.

2) Concerning the use of foams in laser-driven experiments, we discussed about possibility of using foams to increase the process of proton generation as a first step towards increasing alpha particle yield. This follows recent experimental results obtained on the laser Phelix at GSI Darmstadt by the group of Prof. Olga Rosmej. They showed that the interaction of high intensity laser beams with (non-preionised) foam targets brings to an increased production of protons at lower energy, in comparison with the usual TNSA process. Such low-energy protons (E~1 MeV) could indeed be optimal for inducing the hydrogen-boron fusion reactions. This kind of
experiments requires the use of very low-density foams (≤ 10 mg/cc) and at the moment the group at Politecnico has difficulties in obtaining such values, but work is in progress.

3) Another point which is interesting for both groups (Politecnico and CELIA) is the study of the equation of state of foams (eventually including boron) and the experimental determination of the “homogenization time”, i.e. the time needed to fill the pores in the foam following plasma expansion. The determination of such time is important to validate theoretical models. We discussed the possibility of collaborating on this point (and also collaborating with ELI Beamlines in Prague and with the group at ENEA Frascati)

4) Finally, we discussed about the possibility of organising a Summer school on Laser produced Plasmas and laser-driven fusion, possibly in Varenna (on Lake Como in Italy). Such school could be supported by the COST Action PROBONO in June or July 2025

Below are photos taken during the visit at the laboratory and during the seminar.

A21

Grantee name: Matteo Valt

Title: Novel advanced targets for proton-boron nuclear fusion experiment at TARANIS
Start and end date: 06/08/2023 to 13/08/2023

During the week, the grantee has been introduced to all the necessary instrumentation, learn safety instructions, learn the complementary equipment, and familiarize with the people of the Centre for Plasma Physics of the Queen's University of Belfast (CPP-QUB). Moreover, the grantee has gained experience with the experimental setup of the TARANIS laser system. Including laser physics, time of flight (TOF) detector, Thomson parabola (TP) and CR39 detectors as planned. Moreover, Nomarski imaging interferometry has been added to the setup. After this extensive introductory part, commercial Boron Nitride and High-Density Polyethylene targets have been shot as a benchmark. The grantee has taken part to all the procedure involved in a typical proton-boron nuclear fusion experiment. In particular, preparation and organization of CR39 detectors, Target positioning and alignment inside the testing chamber, system pumping-down, electromagnetic pulse (EMP) data acquisition and analysis and CR39 etching in sodium hydroxide solution have been extensively covered and experienced. Subsequently, target developed at FBK have been tested within the TARANIS. In the next few weeks, all the data collected will be analysed by CPP-QUB researcher and data will be discussed together with the FBK team for future collaborations.

This STSM has provided an invaluable opportunity for the grantee to expand his technical and scientific skills at the state-of-the-art laser facility. Thus, the Action MoU objective of enhancing the mobility of early-career researcher is reached. Moreover, some scientific outputs are expected soon. In particular, a good amount of data has been obtained through proton-boron nuclear fusion experiment on ad-hoc engineered targets designed at Bruno Kessler Foundation (FBK) and will be analyzed in the next few weeks. In addition, an abstract on this topic titled "Synthesis of advanced (NH3-BH3) ammonia borane targets at FBK for laser driven proton boron fusion experiments" has been submitted to the 3rd International Workshop on Proton-Boron Fusion in Prague in October 2023. In this context, some preliminary results of the STSM measurement campaign will be presented. The STSM has enhanced the cooperation of experimentalists and material scientists from the Micro-Nano Facility Unit (MNF) of FBK and the CPP-QUB. Finally, the collaboration will continue in future project with the development of further advanced target for Proton-Boron Fusion related applications.

 Test chamber photos on the left and a schematic representation of the experimental setup:

Sample preparation and aligned setup photography to obtain a specific angle in order to fit the experimental setup

Test chamber experimental hall (left), and main participants to the experiment during STSM (Right). In particular, starting from left, Alessandro Milani (PoliMi), Daniel Molloy (QUB) and Matteo Valt (FBK).:

Grantee name: Magdalena Christova

Title: Application of Stark broadening parameters of boron spectral lines for p-B fusion reactions

Start and end date: 15/09/2023 to 30/09/2023

A22 & A24

Grantee name: Diluka Singappuli

Title: Laser Plasma Instabilities studies for shock ignition   
Start and end date: 10/09/2023 to 30/09/2023

Grantee name: Gerard Malka

Title: participation to PALS experiment PRAGUE

Start and end date: 16/09/2023 to 30/09/2023

A completed STSMs carried out by Diluka Singappuli from Universite de Bordeaux (FR) at the ELI Beamlines in Prague (CZ) and continued along with Gerard Malka from Universite de Bordeaux (FR) at the Prague Asterix Laser System (PALS) in Prague (CZ).

Grantee name: Howel Larreur

Title:PALS large-angle SRS

Start and end date: 24/09/2023 to 14/10/2023

  Grantee name: Donaldi Mancelli

  Title: Collaboratice experiment on Caharcterization of SSRS
   and light Scattered outside the Laser Cone at SI intensities

  Start and end date: 25/09/2023 to 14/10/2023

Grantee name: Pierluigi Andreoli
Start and end date: 04/10/2023 to 07/10/2023

Grantee name: Francesco Filippi
Start and end date: 04/10/2023 to 14/10/2023

The applicants went to the PHELIX facility in Darmstadt, German and took part in an experiment focused on the production of a high number of protons in the region of spectrum of major interest for the p-11B resonances.

In this campaign, several aspects of the so-called Super Charge TNSA and laser-target interaction have been investigated. Particular attention was devoted to the efficiency of proton production useful for future p-11B fusion reactions experiments. Htey had also the opportunity to test the diagnostic we developed, and they are going to use, in laser-driven p-11B fusion experiments

During the experiment, they involved to the following tasks

• Mounting and alignment of the Thomson Parabola (TP) diagnostic into the vacuum chamber. Adapting the experimental setup to the particular experimental conditions.
  
  
• Mounting of a copper screen to preserve the IPs from the background noise caused by gamma rays and other radiation produced inside the chamber during the experiment
  
  
• Collecting spectra of protons emitted from the front surface of targets, handling the imaging plates (IP), doing on-site analysis and interpretation of the acquired data to address the upcoming shots.
  
  
• Optimization of the signal through the optimization of the alignment and the selection of the IPs
  
  
• Analysing the relative presence of protons compared to other ions and adapting/optimiz the analysis routine to the particular requests of the experiment.
  
  
• Solving unexpected issues such as discharges on one of the high voltage (HV) channels of the TP and the misalignment of the target before the shot.

The participants had the opportunity to discuss the results analysed during the experimental campaign, in order to decide the experimental plan for the scheduled shots and to plan future experiments finalised to p-11B fusion reaction. The comparison of the previous results obtained with the TP with the results from the other diagnostics, in particular the magnetic spectrometers, allowed to highlight the differences and the similarities between the analysed particle spectra. This preliminary analysis let to determine the follow-up of the experiment.

The experience  they gained during this STSM will be help them to upgrade their diagnostic system in ENEA which required for p-11B experiments. The problem encountered with the HV in the TP will be further investigated and possible upgrades of the diagnostic will be examined 

The data collected with the TP in this experimental campaign will allow for an accurate study of the Super Charge TNSA. The applicants will keep in touch with the group participated to the experiment, with which they had a fruitful exchange of ideas and experience. In the future, this experience may have a strong impact on the p-11B reaction research.