46th International Workshop on High Energy Density Physics with Intense Ion and Laser Beams

Ultra-bright, well-collimated MeV bremsstrahlung radiation was generated through the interaction of high-current electron beams produced via Direct Laser Acceleration (DLA) with a high-Z converter. The DLA mechanism was initiated by a 200 TW, sub-picosecond PHELIX laser pulse at a moderately relativistic intensity of approximately 10¹⁹ W/cm2, delivering about 60 J into pre-ionized,...

The recent progress at the National Ignition Facility (NIF) has sparked fresh excitement around the topic of inertial fusion energy (IFE) [1–5]. However, significant advances are still required before the goal of practical fusion energy can be realised. In particular, while the recently achieved gain of 4 represents an unprecedented milestone [5], it is still short of the minimum value of > 50...

We present the results of the quasi-irrotational approximation developed to deal with the problem of the linear Rayleigh-Taylor instability in incompressible and immiscible non-ideal finite thickness media when the top surface of the layer is attached to a rigid wall, and extend them to the cases in which it is a free surface. These constitute two families of problems that allow for...

We present a unified theoretical and numerical framework for self-similar multi-shock implosions achieving ultra-high compression in a uniform solid spherical target. Extending the classical Guderley model to N-stacked, spherically converging shocks,we derive self-similar solutions and the scaling law for the final density. One-dimensional Lagrangian hydrodynamic simulations confirm this...

The demonstration of energy gain by nuclear fusion in the laboratory and its industrial utilization as an unlimited energy source has been a grand challenge for physicists and engineers for 70 years. This vision has shifted closer to reality after the successful demonstration of multi-megajoule energy yield from deuterium-tritium plasmas in indirectly driven inertial confinement fusion...

We demonstrate an all-optical method for generating ultrashort, spectrally narrow proton beams using an intense laser interaction with a helical target structure. Direct measurements reveal proton pulse durations of only tens of picoseconds, substantially shorter than those obtained from conventional targets at comparable energies. This temporal compression observed is as a result of a...

We report on updates on the comprehensive processing of PIC simulations on HPC systems at LRZ using tools for the data management of large parameter studies of physics simulations. Our example study uses a Particle-In-Cell code by Prof. Ruhl et al (LMU) to explore the laser plasma interaction and ensuing particle acceleration of polysterene or hydrogen micro-targets in the micrometer range....

In this talk, we report on several novel aspects of laser-driven electron acceleration at CALA. The main highlight is the demonstration of energy doubling and a record absolute energy-transfer efficiency from the LWFA to the PWFA stages in hybrid laser–plasma wakefield acceleration (LPWFA). The motivation behind this scheme is to overcome the emittance limits inherent to classical...

A Galilean electromagnetic particle-in-cell (GEM-PIC) algorithm that reformulates the complete Maxwell and Vlasov equations in a Galilean-boosted coordinate frame s developed. This transformation preserves the full electro-magnetic dynamics of the interaction while leveraging scale separation to improve computational efficiency. In contrast to quasistatic approaches, GEM-PIC does not require...

Laser–plasma accelerators promise a compact alternative to conventional radio-frequency accelerators, but achieving simultaneously high charge, high stability, and scalability at high repetition rates remains a major challenge. Here, we demonstrate that self-modulated laser wakefield acceleration (SM-LWFA) driven by picosecond laser pulses provides a robust pathway to generate electron...

The continuous advancement of high‑power laser systems, including those driving inertial confinement fusion experiments, demands optical coatings with exceptionally high laser‑induced damage thresholds (LIDT) and precise control over optical and mechanical properties.

This work presents recent developments in the deposition of high‑LIDT coatings optimized for pulsed laser applications....

A Nd:YLF laser pumped by high-power LEDs

Leon Dauerer1, Ralph Wirth4, Dennis Schumacher2, Florian Wasser3, Markus Roth3,2, and Vincent Bagnoud1,2

(1) GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt, Germany,
(2) Technische Universität Darmstadt, Schlossgartenstrasse 7, 64289 Darmstadt, Germany
(3) Focused Energy GmbH, Im Tiefen See 45, 64293...

The strategy to achieve high gain in Inertial Confinement Fusion (ICF) necessitates flexible laser beamlines capable of delivering diverse temporal characteristics at the kJ energy level. While direct drive target compression demands broad-bandwidth nanosecond pulses, specific ignition schemes require short pulses to generate penetrating particles. Consequently, advanced spectral management is...

The interaction between ultra-short, high-power laser pulses and solid-density targets is frequently utilized to accelerate protons [1-3] and heavier ion species [4]. Since then, it has been shown that structuring the surface leads to enhanced absorption of the laser and enhanced conversion to secondary radiation. Ruhl and Korn [5] have proposed using nanowire arrays with average density near...

The purpose of the presentation is to introduce Marvel Fusion’s high-gain fusion target philosophy. The company’s high-gain target concept incorporates a novel fast-ignition element capable of delivering up to multiple megajoules of fast-ignition energy into dense fuel. In addition, the concept includes a mild compression element that can be validated at existing implosion facilities....

Here, we discuss the hotspot ignition condition for scenarios relevant for applications in the field of inertial fusion energy. Different tradeoffs of compression and hotspot energy are considered. Special attention is paid to the necessary modifications of the condition for a novel class of fusion fuels, so-called "non-cryogenic DTs". These fuels, recently proposed by Ruhl et al. (2025),...

Inertial Confinement Fusion (ICF) remains a promising pathway for high-gain energy production, yet achieving ignition conditions requires precise control over fuel compression and thermal transport. A promising avenue to relax these stringent requirements is the application of strong external magnetic fields. In this work, we investigate the viability of magnetically assisted heating, where...

We report on further simulations for an experiment studying hot-electron transport in a magnetized planar target conducted on the OMEGA-EP laser system [1]. The magnetic field strength was set at 20 Tesla, which is sufficient to divert hot electrons and hinder their propagation toward a copper fluor layer. By analysing the heating of that layer by hot electrons both with and without the...

Foam-based targets are appealing for driving high-efficiency radiation-matter coupling in high-energy-density and high-intensity physics experiments [1-4]. In particular, low-density foams enable the generation of a near-critical plasma in which laser pulses with relativistic field strength, $a_0$ ≫ 1, propagate. In this plasma, the laser delivers its energy to a large number of electrons and...

Highly ordered nanowire arrays with sub-wavelength diameter can be engineered to absorb multi-PW laser pulses with ultra-high-contrast (<10$^{-12}$ on ps timescales), sub-100-fs pulse duration at intensities above 10$^{20}$ W/cm$^2$ with efficiency nearing 100%. A large fraction of the absorbed energy is converted to high-current ion and electron flows in a controlled manner by this Nano...

We present a novel, more general analytic solution for the moments of the Boltzmann collision operator. Such moments are essential for deriving hydro equations and their nonthermal extensions. To the best of our knowledge, they have so far only been evaluated for specific models, cross-sections, small nonthermal contributions, and small relative velocities. We overcome these limitations by...

A brief description of the five moment model of Hydrodynamics for Coulomb collisions is given. The model includes large angle collisions. The corresponding integrals are evaluated to logarithmic and constant order in the maximum impact parameter. The Bethe formula is recovered in the appropriate limit.
This model is then self-consistently coupled to a deuterium-tritium plasma of a given...

We derive a generalized Beth-Uhlenbeck formula for the entropy as well as the density, of a dense fermion system with strong two-particle correlations, including scattering states and bound states. We work within the $\Phi-$derivable approach to the thermodynamic potential. The formula takes the form of an energy-momentum integral over a statistical distribution function times a unique...

The transition of Inertial Fusion Energy (IFE) from scientific ignition to a viable power source depends on the ability to mass-produce complex, high-precision targets — specifically low-density polymer foams and shells — at repetition rates exceeding 10 Hz.
While Two-Photon Polymerization (2PP) offers the necessary sub-micron resolution for controlling foam morphology, standard...

The realization of Inertial Fusion Energy (IFE) requires target injection rates of approximately 10$\,$Hz. Furthermore, a perfectly homogeneous Deuterium-Tritium (DT) layer inside the target is strictly required, as even minor asymmetries in the fuel distribution will amplify during implosion, preventing ignition. To meet this demand while minimizing the active Tritium inventory, wetted foams...

Achieving inertial fusion energy (IFE) requires laser systems capable of delivering hundreds of high-power, high-repetition-rate beams with exceptional stability. The ALADIN project (Adaptive Laser Architecture for Dynamic INertial fusion) addresses this challenge by developing adaptive laser control technologies that enable reliable, repeatable fuel compression in direct-drive IFE schemes....

Modern high-intensity laser systems are required to provide higher repetition rate, greater stability and higher output energy with increased wall-plug efficiency. In recent years, diode pumping has become a central theme in the development of new laser systems. With narrowband emission and precise current control, laser diodes offer higher efficiency and more stable output than...

In the worldwide pursuit of achieving energy production via inertial confinement fusion, the development of large laser infrastructures has experienced a renaissance. Advances in laser technology are being driven not only by the need to enhance laser performance and efficiency but also by the stringent requirements imposed by modern approaches to improve the overall efficiency of the fusion...

High-energy electrons have many applications, ranging from medical physics to fundamental research. Laser wakefield acceleration (LWFA) is a new method of accelerating electrons to high energies in mere centimeters, as opposed to hundreds of meters using classic linear accelerators. Electrons accelerated with LWFA can also be used to drive Laser-Driven Neutron Sources (LDNS). In this process,...

The Laser Ion Generation, Handling and Transport (LIGHT) beamline at GSI Helmholtzzentrum für Schwerionenforschung GmbH enables advanced phase-space manipulations of laser-generated ion beams. In recent years, the LIGHT collaboration has successfully generated and focused intense proton and ion bunches with sub-nanosecond durations, opening pathways to applications such as probing ion-stopping...

Electron-phonon coupling is a fundamental process governing the energy relaxation dynamics of solids excited by ultrashort laser pulses. While this coupling is often described in terms of an effective electron temperature, recent works have highlighted the important roles of both nonequilibrium electronic distributions and detailed phononic properties.

In this study, we investigate how...

Experimental and numerical results regarding underwater electrical explosion of single wires, cylindrical and spherical wire arrays and strong shock waves generation will be presented. Application of this approach for studies of high energy density matter, supersonic water jet generation, shock generation in a target and will be discussed as well.

The generation of coherent attosecond pulses of radiation in the extreme ultraviolet (XUV) range provides the required spatial and temporal resolution to study a wide range of phenomena involving fast electron dynamics. [1]

Single sub-femtosecond XUV pulses as well as near-PHz repetition rate trains of such pulses have been demonstrated from gas targets however these are far too weak for...

X-ray sources are of growing importance as a diagnostic tool for fundamental research in High Energy Density (HED) physics and Inertial Confinement Fusion (ICF) studies. These applications deploy so-called x-ray backlighters to probe the interior of the plasma, which should ideally have a low divergence, small source size, to achieve a sufficient imaging resolution, and high brightness to...

We aim to explore laser ablation as a possible approach for creating clean, well-defined microholes in polymers used for lase fusion targets where symmetry and control of surface roughness are important. Because polymers differ widely in their properties, general insights into laser–material interaction are sought through modeling of density-dependent excitation in band-gap materials.
The...

Advances in high-energy-density physics increasingly require well-defined, targets that can shape the interaction of intense laser and ion beams. Traditional target fabrication methods, particularly for low-density foams, often produce stochastic microstructures with limited control over geometry, uniformity, and feature size.
In this work, we demonstrate the use of two-photon...

Ultrafast optical excitation of metals induces a non-equilibrium energy distribution in the electronic system, with a characteristic step-structure determined by Pauli blocking. On a femtosecond timescale, electron-electron scattering drives the electrons towards a hot Fermi distribution.
In this work, we present a derivation of the full electron-electron Boltzmann collision integral within...

A new target area is set up at the Helmholtz Institute Jena. One central aspect are combined experiments with the laser systems JETi200 and POLARIS. Additionally, a new dedicated probe laser system, JETi ONE, was installed giving the opportunity to investigate laser-plasma interactions with few-cycle laser pulse ranging from the visible to the mid infrared spectrum. In a first step, we...

In this contribution, we present results from a long-term experimental study of electron, electromagnetic, and ion emission at the iodine laser system PALS (wavelength 1315 nm, pulse duration 0.3 ns, up to 700 J on target). Charged-particle emission was investigated using a comprehensive set of diagnostics, including magnetic spectrometers and differential absorption spectrometers deployed at...

The Breit-Wheeler pair production experiment, under the project FOR2783[1], requires laser operation near the damage threshold of the turning mirror. Due to the experiment's inherently low cross section, a high number of laser shots is essential. Consequently, the selection of the mirrors and the geometry must be optimized to maximize shot count without exceeding damage limits. To support...

Shock–cloud interactions are a fundamental process in astrophysics, governing whether interstellar clouds collapse to form stars or are disrupted and dispersed into the surrounding medium. Laboratory astrophysics experiments provide a controlled platform to investigate the complex hydrodynamics involved in these interactions. In a experiment at the LULI2000 laser facility, we generated a...

The Facility for Antiproton and Ion Research (FAIR) is currently under construction and will start operations with first nuclear physics experiments in 2027. FAIR will offer unique high-intensity heavy ion beams and proton beams that will also be used by the HED@FAIR collaboration for warm dense matter (WDM) experiments. Three main experimental setups will be used by HED@FAIR for experiments:...

Dynamic compression of carbon-rich materials provides a pathway to nanodiamond formation [1-3] under extreme pressure–temperature conditions comparable to those of ice-giant interiors, where diamond precipitation has been proposed to influence planetary structure and evolution. Laser-driven shock experiments at x-ray free-electron lasers enable in situ, time-resolved characterisation of...

High-intensity laser interactions with solid targets generate powerful radiofrequency and microwave electromagnetic pulses (EMP) that scale with laser energy and intensity. The fundamental origins and underlying physical mechanisms of laser-induced EMP emission remain an unresolved challenge in high-energy-density physics, necessitating more sophisticated diagnostic and modeling approaches....

The structure of liquid carbon[1] and the formation of nanodiamonds under dynamic compression[2, 3] sparked scientific interest. The extreme conditions required were generated for a few nanoseconds using the HED-HIBEF instrument at EuXFEL[4] by the DiPOLE-100X laser. Laser-induced shock compression was utilised to compress glassy carbon, reaching Mbar pressures. For probing, X-ray Thomson...

Dynamically shock compressing plastics like polystyrene [PS, (C$_{8}$H$_{8}$)$_{\text{n}}$] or polyethylene terephthalate [PET, (C$_{10}$H$_{8}$O$_{4}$)$_{\text{n}}$] to Mbar pressures accesses a regime with peculiar phenomena, like carbon de-mixing and subsequent formation of diamond crystallites $^{[1,2]}$ or the predicted appearance of metallic hydrogen $^{[3]}$, that are expected to impact...

Hydrogen is becoming an increasingly important energy carrier in the context of sustainable energy systems. Consequently, there is strong interest in developing methods for hydrogen production that are both environmentally benign and energy efficient. Established production routes either rely on fossil fuels with significant CO₂ emissions or suffer from comparatively low overall...

Laser-accelerated ions typically exhibit an exponential energy spectrum up to a characteristic cut-off energy, which is a signature of target normal sheath acceleration (TNSA) [1]. This broad energy distribution inherent to TNSA poses a significant limitation for applications requiring well-defined ion energies, such as proton therapy [2] and the fast ignition concept in inertial confinement...

The EU-funded THRILL project (Technology for High-Repetition-Rate Intense Laser Laboratories) has the goal to identify the most appropriate architecture of the next generation high-energy (kJ-class) lasers to be used in combination with the large-scale European research facilities Eu-XFEL and FAIR. Here the increase of the repetition rate from few shots per day the one shot per few minutes...

Understanding radiative energy transport in stellar interiors requires accurate knowledge of the opacity of dense hydrogen plasmas, yet direct experimental constraints in the relevant regime have been absent. We report measurements of hydrogen opacity at extreme densities—up to ~800× solid density—and temperatures of a few million kelvin, achieved through a tailored low-velocity capsule...

States of extreme energy density – i.e., matter under high pressures and extremely high temperatures – are found in the interiors of planets (megabar pressures, several thousand kelvins) or stars (gigabar pressures, several million kelvins) and are highly relevant for the ultimate application of clean and reliable energy production by inertial fusion. A deep understanding of the complicated...

The investigation of equations of state, physical properties, and phase transitions of materials under extreme high-pressure conditions is a fundamental challenge in condensed matter physics and planetary science. Recent advancements in laser-driven compression techniques allow us to replicate these extreme states in laboratory settings, achieving terapascal (TPa) pressures, temperatures...

Ion stopping in dense plasmas is fundamental for understanding the plasma transport properties with direct implications for inertial confinement fusion, high-energy-density physics and laboratory astrophysics. This process remains poorly understood when the ion-plasma coupling parameter exceeds unity - a nonlinear regime where non-perturbative screening play an important role. We report a...

Relativistic oscillating plasma mirrors provide a promising platform for generating bright high-harmonic radiation and, ultimately, extreme electromagnetic fields. Theory predicts that, under optimized conditions, these systems can strongly compress laser energy in space and time, forming a Coherent Harmonic Focus (CHF) with intensities orders of magnitude beyond those of the driving pulse....

Efficiency limit relativistic harmonic generation from solid targets (ROM) has recently been demonstrated experimentally. Multi-petawatt laser facilities will soon be able to harness this mechanism to generate intense coherent attosecond harmonic foci suitable for probing the quantum vacuum via fully optical means. However, experiment has demonstrated that efficiency scaling with harmonic...

Precise control over the temporal profile of the incident laser radiation in ultra-relativistic plasma interactions is crucial for many applications. While the effects of laser contrast on longer timescales have been studied and methods of control are well known, here we investigate the impact of the rising edge within a few picoseconds of the peak intensity of the pulse. As laser powers...

Quantum field theory predicts that the vacuum exhibits a nonlinear response to strong electromagnetic fields, giving rise to phenomena such as vacuum birefringence. Despite its fundamental significance, this effect has remained experimentally inaccessible and has yet to be observed in the laboratory. Detecting it would provide a distinct signature of the optical activity of the quantum vacuum...

Inertial Confinement Fusion (ICF) is one of the critical technical approaches to achieving controlled fusion energy. The successful achievement of ignition at the National Ignition Facility (NIF) has further confirmed the technical feasibility of ICF. However, although the ignition has been achieved, research into higher gains and lower driving conditions remains an important next step. Laser...

In the interaction of ns laser pulses with plasma, a large amount of highly energetic electrons stems from laser plasma instabilities (LPIs). These describe the scattering of a large percentage of laser photons on ion acoustic or electron plasma waves, with unbound electrons being accelerated in the resulting fields of the latter.
By adjusting the incident laser light, LPIs can be modulated...

Research activities on heavy-ion fusion (HIF) were abandoned over a decade ago, and brought down to a crawl even earlier. It is easy to forget that in the 90's HIF was considered to be the top contender for developing inertial fusion energy (IFE). This is not surprising: accelerator technology is well-established, and the conversion efficiency from a wall plug to accelerated particles is hard...

In the pursuit of the realization of an Inertial Fusion Energy (IFE) reactor, directly driving the fuel capsules with laser beams is a compelling design choice due to the more efficient energy coupling compared to indirect drive. However, the laser illumination symmetry necessary for achieving ignition and gain imposes stringent accuracy requirements on the laser system.
We present a reactor...

High power laser systems driving relativistic plasmas have applications in the generation of high energy, short duration particle and photon secondary sources. These mechanisms are typically extremely sensitive to laser contrast - pre-pulses and amplified spontaneous emission (ASE) that can trigger an expanding plasma long before the peak intensity is reached. As we enter the multi-petawatt...

Fast neutron-induced nuclear reactions are crucial for advancing our understanding of fundamental nuclear processes, stellar nucleosynthesis, and applications, including reactor safety, medical isotope production, and materials research. As many research reactors are being phased out, compact accelerator-based neutron sources are becoming increasingly important. Laser-driven neutron sources...

Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871, Japan

Laser-driven proton acceleration has long been limited by an apparent trade-off between laser-to-ion conversion efficiency and maximum particle energy. While target-normal-sheath acceleration (TNSA) remains robust, it typically suffers from low efficiency and thermal-like spectra at the multi-MeV level. Here we...

With the goal of investigating the creation of extremely neutron rich isotopes around the waiting point of the rapid neutron capture process (r-process) at N=126, Habs et al. [1] proposed the so-called fission-fusion reaction mechanism. This mechanism exploits the inherently nearly solid-state bunch density of laser ion accelerated ions, resulting high cross-sections for the creation of exotic...

Magnetic lens-based proton radiography is a unique and powerful diagnostics technique capable of resolving ultra-fast processes on the ns-scale in dense matter with unprecedented micrometer spatial resolution. Recently, the PRIOR-II proton radiography facility has been designed, constructed and commissioned at the GSI Helmholtz Centre for Heavy Ion Research, pushing the technical boundaries of...

The HHT experiment area at GSI offers the unique capability to heat matter by intense bunches of high-energy heavy-ions from the SIS-18 heavy-ion synchrotron and to probe the generated short-lived states with X-rays created by the PHELIX laser facility. Focusing ~300-ns-long bunches of up to $4\times 10^9$ $\text{U}^{73+}$ ions down to sub-millimeter spot-sizes, aluminum samples were heated to...

The graphitization-threshold of diamond is of significant interest for nanodiamond synthesis from laser-shocked plastics, for particle detectors, and for the application in diamond anvil cells.
We report on experiments conducted at the HHT facility (GSI), in which a monocrystalline diamond target was volumetrically heated using a uranium ion beam. The PHELIX laser enabled measurements of...

Accurately determining the ionization state of warm dense carbon is critical
for predictive modeling in high-energy-density physics, particularly for inertial
confinement fusion experiments and for advancing the understanding of astro-
physical systems such as white dwarf envelopes [1,2]. However, obtaining direct
measurements under the relevant extreme conditions remains challenging....