ARISE: an algorithm for rapid ion spectrum extraction enabling real-time optimization in high-repetition-rate laser-driven ion acceleration

Experimental researches using high power optical lasers combined with free electron lasers (FELs) open new frontiers in high energy density (HED) sciences. Probing and pumping capabilities are dramatically improved due to the brightness of the XFEL pulses with ultrafast duration. Besides, the peak intensities of Ti:sapphire laser Chirped Pulse Amplification (CPA) systems reach petawatt (PW)-class with operating in few tens of fs and commercially available at a few Hz of repetition rate. We have been developing an experimental platform for HED sciences using high power, high intensity optical lasers at the XFEL facility, SACLA.Currently, an experimental platform with a dual 0.5 PW Ti:Sapphire laser system is under beam commissioning for experiments combined with the SACLA’s x-ray beam for research objectives that require more peak power in the optical laser pulses with a few tens of fs. The optical laser system is designed to deliver two laser beams simultaneously with the maximum power of 0.5 PW in each into a target chamber located in an experimental hutch 6 (EH6) at BL2, which was recently commissioned as a SACLA’s 2nd hard x-ray beamline. A focusing capability using sets of compound refractive lenses will be applied to increase the x-ray fluence on the target sample. One of the most key issues for the integrated experimental platform is development of diagnostics that meets requirements both from the high power laser (e.g. resistance to harsh environments) and from the XFEL (e.g. adaptation to the available data acquisition system). The status and future perspective of the development including automatic laser alignment systems will be reported in the presentation. We will discuss the most promising and important new physics experiments that will be enabled by the combination of PW-class lasers and the world-class FEL’s x-ray beam.

This article reports the development, construction, and experimental test of an angle-resolved Thomson parabola (TP) spectrometer for laser-accelerated multi-MeV ion beams in order to distinguish between ionic species with different charge-to-mass ratio. High repetition rate (HHR) compatibility is guaranteed by the use of a microchannel plate (MCP) as active particle detector. The angular resolving power, which is achieved due to an array of entrance pinholes, can be simply adjusted by modifying the geometry of the experiment and/or the pinhole array itself. The analysis procedure allows for different ion traces to cross on the detector plane, which greatly enhances the flexibility and capabilities of the detector. A full characterization of the TP magnetic field is implemented into a relativistic code developed for the trajectory calculation of each pinhole beamlet. We describe the first test of the spectrometer at the VEGA 3 laser facility at CLPU, Salamanca (Spain), where up to protons and carbon ions from a laser-irradiated Al foil are detected.

Hardware-in-the-loop (HIL) simulation has been widely used in systems development and algorithm verification in many fields. This paper presents a simulation system by using this method in the field of wireless communication. The simulation system is composed of control panel, software module and hardware module. Distribute interactive simulation, collaboration between different subsystems and data security can be accomplished through main control and management. In the part of hardware, we design Ethernet-oriented protocol for module communication and control executive module realized in FPGA (Cyclone IV 4CE115). At last, we introduce energy detection algorithm based on Neyman-pearson criterion which is verified in this system. The result shows that simulation system can accomplish complex simulation by means of data and resource analysis and parameter optimization in real time.

We report on the experimental characterisation of laser-driven ion beams using a Thomson Parabola Spectrometer (TPS) equipped with trapezoidally shaped electric plates, proposed by Gwynne et al. [Rev. Sci. Instrum. 85, 033304 (2014)]. While a pair of extended (30 cm long) electric plates was able to produce a significant increase in the separation between neighbouring ion species at high energies, deploying a trapezoidal design circumvented the spectral clipping at the low energy end of the ion spectra. The shape of the electric plate was chosen carefully considering, for the given spectrometer configuration, the range of detectable ion energies and species. Analytical tracing of the ion parabolas matches closely with the experimental data, which suggests a minimal effect of fringe fields on the escaping ions close to the wedged edge of the electrode. The analytical formulae were derived considering the relativistic correction required for the high energy ions to be characterised using such spectrometer.

Ion acceleration is considered to be one of the main applications of high power laser systems that are being projected, have been built, or are already operational around the world. Laser driven ion acceleration is not only attractive from the point of view of potential applications of high energy ion beams, but also from the point of view of investigations of fundamental aspects of laser-matter interaction and advanced concepts of particle acceleration. In this talk we, first, discuss an experimental study of ion acceleration using the BELLA petawatt laser, and, second, the results of 3D PIC modeling of laser ion acceleration from near critical density (NCD) targets. We report on parameter scans with >100 shots that were enabled by the high repetition rate (1 Hz) of the laser, targetry and diagnostic. The experiments were conducted in the large laser spot size regime, where we found that the geometry of the interaction plays an important role in providing uniform plasma heating across the focal plane. The laser pulse duration scans (35 - 600 fs) were instrumental in revealing this geometric effect. Particle-in-Cell (PIC) simulations were used to gain insight into the dynamics of the interaction and field structure. Laser-driven ion acceleration via the Magnetic Vortex Acceleration (MVA) scheme was explored using 3D Warp+PICSAR and WarpX PIC simulation codes. We discuss the properties of the Magnetic Vortex Acceleration mechanism revealed through the 3D PIC simulations and its optimization through matching of laser pulse focusing and target density. The work was supported by the US DOE Office of Science (HEP, FES, and LDRD) under Contract No. DE-AC02-05CH11231.

Strong multi-kilotesla magnetic fields have various applications in high-energy density science and laboratory astrophysics, but they are not readily available. In our previous work [Y. Shi et al., Phys. Rev. Lett. 130, 155101 (2023)], we developed a novel approach for generating such fields using multiple conventional laser beams with a twist in the pointing direction. This method is particularly well-suited for multi-kilojoule petawatt-class laser systems like SG-II UP, which are designed with multiple linearly polarized beamlets. Utilizing three-dimensional kinetic particle-in-cell simulations, we examine critical factors for a proof-of-principle experiment, such as laser polarization, relative pulse delay, phase offset, pointing stability, and target configuration, and their impact on magnetic field generation. Our general conclusion is that the approach is very robust and can be realized under a wide range of laser parameters and plasma conditions. We also provide an in-depth analysis of the axial magnetic field configuration, azimuthal electron current, and electron and ion orbital angular momentum densities. Supported by a simple model, our analysis shows that the axial magnetic field decays owing to the expansion of hot electrons.

High-energy and high-intensity lasers are essential for pushing the boundaries of science. Their development has allowed leaps forward in basic research areas, including laser–plasma interaction, high-energy density science, metrology, biology and medical technology. The Helmholtz International Beamline for Extreme Fields user consortium contributes and operates two high-peak-power optical lasers using the high energy density instrument at the European X-ray free electron laser (EuXFEL) facility. These lasers will be used to generate transient extreme states of density and temperature to be probed by the X-ray beam. This paper introduces the ReLaX laser, a short-pulse high-intensity Ti:Sa laser system, and discusses its characteristics as available for user experiments. It will also present the first experimental commissioning results validating its successful integration into the EuXFEL infrastructure and viability as a relativistic-intensity laser driver.

In order to reduce the torque ripple and running loss caused by the commutation error in the brushless DC motor (BLDCM) of the magnetically suspended control moment gyroscope (MSCMG), this study proposes a novel method dealing with commutation error in sensorless controlled BLDCM by rapid phase extraction and compensation technique. First, a traditional virtual neutral point circuit consisted of three-phase resistance network and low-pass filter are used to obtain the zero-crossing points of the non-conducting phase back electromotive force without noise interference. Then, an improved phase extraction method is built after analysing the DC-link current. Commutation error is extracted from DC-link current with the improved phase extractor rapidly. Furthermore, the effect of speed offset caused by fluctuation during phase extraction is also analysed and an adaptive commutation error compensation method based on the DC-link current phase extraction is proposed. Finally, simulation and experimental results performed on the high-speed motor of MSCMG verify its effectiveness and rapidity. The main novelties of this study are the direct phase extraction algorithm with natural parameter insensitivity and robustness and the rapid iterative commutation error compensation method based on the extraction algorithm.

This paper presents an experimental and theoretical study of betatron x-ray radiation from laser wakefield acceleration in the self-modulated regime. Our experiments use picosecond duration laser pulses up to 150 J, for plasmas with electronic densities on the order of 1019 cm−3. In the self-modulated regime, electrons accelerated in the wake of the laser pulse are subject to both the longitudinal plasma and transverse laser electrical fields. As a result, they undergo oscillations and radiate a synchrotron-like spectrum. In our experimental configuration, electrons accelerated up to about 300 MeV, as well as betatron x-ray spectra with energies of 10 s of keV and photon fluxes between 108–1010 photons/eV/Sr are reported. Our experiments open the prospect of using betatron x-ray radiation for applications, and the source could be competitive with current x-ray backlighting methods on multi-kilojoule laser systems used for high energy density or fusion sciences.

An algorithm for fast extraction and identification of star target

In order to adapt to various complex lane environments, a general fast lane extraction algorithm was proposed. Firstly, according to the mutability of the local gray value and the characteristics of image saliency, the collected road image was preprocessed, and the region of interest was obtained by the proposed double threshold algorithm. Only in the significant region of the road were the image gray value change and image smoothing carried out to solve the problems of consuming too much time and poor noise resistance in lane detection. The lane line edge was then extracted based on the improved Canny operator. When the Otsu threshold was selected, the Kalman filter algorithm was introduced to quickly predict the optimal threshold of the subsequent image sequence in accordance with the characteristics of optimized autoregressive data processing.. Finally, for the straight line fitted by the Hough transform, an effective multi-layer evaluation function was established to realize the online correction of lane lines. Compared with the traditional lane line extraction algorithm, the experimental results show that the proposed algorithm has better accuracy, real-time performance and robustness.

Rapid and inexpensive NaOH based direct PCR for amplification of nuclear and organelle DNA from ramie (Boehmeria nivea), a bast fibre crop containing complex polysaccharides

Parameter extraction of solar cell models using improved shuffled complex evolution algorithm

Automatic fingerprint identification systems use level-1 and level-2 features for fingerprint identification. However, forensic examiners utilize inherent level-3 details along with level-2 features. Existing level-3 feature extraction algorithms are computationally expensive to be used for identification. This paper presents a novel algorithm for fast level-3 feature extraction and identification. The algorithm starts with computing local image quality score using redundant discrete wavelet transform. A fast curve evolution algorithm is then used to extract four level-3 features namely, pores, ridge contours, dots, and incipient ridges. Along with level-1 and level-2 features, these level-3 features are used in a Delaunay triangulation based indexing algorithm. Finally, quality-based likelihood ratio is used to further improve the identification performance. Experiments conducted on a high resolution fingerprint database containing rolled, slap and latent images indicate that the algorithm offers significant benefits for fast fingerprint identification.

Algorithms for fast multidimensional signal extraction