Demanding applications like radiation therapy of cancer have pushed the development of laser proton accelerators and defined necessary proton beam properties as well as levels of control and stability.
The presentation will give an overview of the recent experiments for laser driven proton acceleration employing a cryogenic target system which is capable of producing a renewable and debris...
Over-dense gas targets are attractive for ion acceleration since they can provide debris free, high repetition sources of pure ion beams. The spatial profile of gas targets are typically not well suited for laser-plasma energy coupling, however, this can be improved by the addition of an optical prepulse which launches a blast-wave into the plasma. This technique has previously been shown to...
Target Normal Sheath Acceleration (TNSA) is arguably the most robust and well known laser-driven ion acceleration scheme, nevertheless it has one main issue, namely the low efficiency of laser conversion into energetic ions. In order to overcome this limit, one possibility is to use a double-layer target with a near-critical coating [1]. Nevertheless, the electron critical density for the...
Laser-driven ion acceleration promises to provide a compact solution for demanding applications like particle therapy, proton radiography or inertial confinement research. Controlling the particle beam parameters to achieve these goals is currently pushing the frontier of laser driven particle accelerators.
The performance of the plasma acceleration is strongly dependent on the complex...
Laser-accelerated protons have a great potential for innovative experiments in radiation biology and chemistry due to the ultra-high dose rate (109 Gy/s) delivered in nanosecond time scale. However, the broad angular divergence around the propagation axis makes them not optimal for applications with stringent requirements on dose homogeneity and total flux at the target. The simplest solution...
Investigating the energy loss of ions in plasma is a long standing research topic of the plasma physics group at GSI. In particular at low particle velocity, which corresponds to the maximum of the stopping power, the theoretical descriptions based on perturbative approaches fail and models show a discrepancy. This lack of understanding is particularly critical and could be a reason for the...
The interaction of short intense pulses with solid targets is known for the acceleration of ions by the target normal sheath acceleration mechanism. After the ions are accelerated they are assumed to drift in space towards the detector. During this time, the temperature of the plasma is understood to be significantly high such that recombination is prevented and all the ions that are...
Laser-driven proton acceleration, as produced during the interaction of a high-intensity (I>1x10^18 W/cm^2), short pulse (<1 ps) laser with a solid target, is a prosperous field of endeavor for manifold applications in different domains, including astrophysics, biomedicine and materials science. These emerging applications benefit from the unique features of the laser-accelerated particles...
B. Dromey, M. Coughlan, N. Breslin, H. Donnelly, C. Arthur, S. White, M. Yeung,
School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
b.dromey@qub.ac.uk
Understanding the effects of ion interactions in condensed matter has been a focus of research for decades. While many of these studies focus on the longer term effects such as cell death or material integrity, typically this is performed using relatively long (>100 ps) proton pulses from radiofrequency accelerators in conjunction with chemical scavenging techniques [1]. As protons traverse a...
Invention and application of chirped pulse amplification technique in short pulse laser has been leading to unprecedented ultra high laser peak power[1]. After more than three decade development, a few petawatt class lasers, whose pulse durations vary from a few femtoseconds to several picoseconds, have been built up around the world[2]. The focused laser intensity goes beyond 1021W/cm2. ...
Nowadays’ research on laser-driven proton acceleration is focusing on the interaction of relativistic-intensity laser pulses with sub-micrometer targets. With such targets, a variety of acceleration mechanisms can be studied, from the robust TNSA to more advanced schemes that predict better performances in particle energy and beam parameters. The ideal conditions for this type of studies are...
The interaction of relativistically intense short pulse (~few tens of fs) laser pulse with solid material generates quasi-static electric fields with strengths of > TV/m are produced within a short distance of less than $\mu$m [1]. Thanks to the very strong field gradient, the field can accelerate ions beyond MeV within a micron. Unlike the acceleration of low-Z ions, acceleration of the...
Recently the ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) beamline has been installed at ELI-Beamlines in the Czech Republic. The main goal of ELIMAIA is to offer short ion bunches accelerated by lasers with high repetition rate to users from different fields (physics, biology, material science, medicine, chemistry, archaeology) and, at the same time, to demonstrate...
Laser-driven ion sources exhibit unique beam properties that open up application opportunities but also pose challenges. Especially the large source divergence (~ 20° half angle) as well as the broad energy bandwidth (100%) of laser-accelerated ion bunches limit their applicability. Yet, temporal structure (~ps bunch durations) and intensity ($10^{13}$ ions per bunch) have roused interest for...
We present the technological advancements of recent years at the laser-driven ion acceleration experiment at the ATLAS 300 laser in Garching near Munich that enabled a first application oriented experiment. Improvements were made in target positioning, proton transport and diagnostics as well as in specimen handling and their capabilities explored by performing an irradiation experiment with...
A high repetition rate target assembly for laser-plasma acceleration has been built at the Laser Laboratory for Acceleration and Applications (L2A2) of the University of Santiago de Compostela. The target consists on two linear stages combined with a rotational one to ensure the focusing and refreshment of the target material shot-by-shot. A multi-target wheel alow us to install different...
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. When they randomly bond with each other by van der Waals forces, so-called carbon nanotube foam (CNF) is formed. The average density of CNFs lies in the range of a few mg/cm^3 to tens of mg/cm^3. If fully ionized, such a thin foam can turn to a plasma slab with critical density. Here we report the recent progress on...
Many of the underlying mechanisms for laser-driven ion acceleration exploit the interaction of an ultra-intense laser pulse with sub-micrometer thin foils. These mechanisms rely on well-defined plasma conditions at the time of the maximum laser intensity. These conditions, especially the preplasma scale length, are extremely hard to measure and remain mostly not known, which prevents a...
Spectral signatures of laser-accelerated ion beams are frequently used to characterize underlying acceleration mechanisms. Yet regularly, more than just one ion species are accelerated in experiments, e.g. from hydro-carbon contamination layers, multiple charge states or mixed materials. Such presence of multiple ion species ($q/m$) in the accelerating field leads to characteristic modulations...
We present results from a laser-driven proton acceleration experiment performed at the JETI 40 laser system in Jena, Germany. Here, we investigated the influence of the position of water micro-droplets relative to the laser’s focus along the polarization axis on the maximum kinetic energy of accelerated protons, either for a steep plasma gradient or an additional pre-plasma. The first case was...
Thin aluminium foils irradiated by ultraintense femtosecond-long laser pulses have been extensively used in the last two decades for MeV-range proton beam generation. In the early stage of the interaction, a dense cloud of electrons is directly accelerated by the laser, pass through the target and ionize its rear surface. Here, an extremely high quasi-static electric field (of the order of...
As the community prepares for the next generation of laser facilities coming online in the near future, attention will shift towards advanced mechanisms such as the radiation pressure acceleration (RPA) which has been predicted to be the dominant ion acceleration mechanism at intensities >10$^{22}$W/cm2 [1]. Recent studies have shown that current facilities can also enter this regime by...
In this contribution, we present the result of an investigation of foam-based targets for laser-driven ion acceleration. The study was performed in collaboration between the Laser-Particle Acceleration group at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the Nanolab group at Politecnico di Milano.
Foam targets used in this experiment are composed of µm-thick solid foils with ultra-low...
Laser-driven ion fast ignition (IFI) of fusion targets requires ultra-intense ion beams with parameters whose approximate values are estimated to be as follows (e. g. [1]): the mean ion energy ~10 – 50 MeV/nucleon, the beam intensity ~10^20
W/cm2, the beam fluence ~1 GJ/cm2, the ion pulse duration ~1 - 10 ps, and a total beam energy of ~10 – 20 kJ. To achieve these parameters, an effective...
