For many years, laser-driven ion acceleration, mainly proton acceleration, has been proposed and a number of proof-of-principle experiments have been carried out with lasers whose pulse duration was in the nanosecond range. In the 1990s, ion acceleration in a relativistic plasma was demonstrated with ultra-short pulse lasers based on the chirped pulse amplification technique which can provide not only picosecond or femtosecond laser pulse duration, but simultaneously ultra-high peak power of terawatt to petawatt levels. Starting from the year 2000, several groups demonstrated low transverse emittance, tens of MeV proton beams with a conversion efficiency of up to several percent. The laser-accelerated particle beams have a duration of the order of a few picoseconds at the source, an ultra-high peak current and a broad energy spectrum, which make them suitable for many, including several unique, applications. This paper reviews, firstly, the historical background including the early laser-matter interaction studies on energetic ion acceleration relevant to inertial confinement fusion. Secondly, we describe several implemented and proposed mechanisms of proton and/or ion acceleration driven by ultra-short high-intensity lasers. We pay special attention to relatively simple models of several acceleration regimes. The models connect the laser, plasma and proton/ion beam parameters, predicting important features, such as energy spectral shape, optimum conditions and scalings under these conditions for maximum ion energy, conversion efficiency, etc. The models also suggest possible ways to manipulate the proton/ion beams by tailoring the target and irradiation conditions. Thirdly, we review experimental results on proton/ion acceleration, starting with the description of driving lasers. We list experimental results and show general trends of parameter dependences and compare them with the theoretical predictions and simulations. The fourth topic includes a review of scientific, industrial and medical applications of laser-driven proton or ion sources, some of which have already been established, while the others are yet to be demonstrated. In most applications, the laser-driven ion sources are complementary to the conventional accelerators, exhibiting significantly different properties. Finally, we summarize the paper.

https://iopscience.iop.org/article/10.1088/0034-4885/75/5/056401/pdf

Review of laser-driven ion sources and their applications.

This review describes induction coil sensors, which are also known as search coils, pickup coils or magnetic loop sensors. The design methods for coils with air and ferromagnetic cores are compared and summarized. The frequency properties of coil sensors are analysed and various methods for output signal processing are presented. Special kinds of induction sensors, such as Rogowski coil, gradiometer sensors, vibrating coil sensors, tangential field sensors and needle probes are described. The applications of coil sensors as magnetic antennae are also presented.

/pdf/induction-coil-sensors-a-review-19wdku49yx.pdf

Induction coil sensors—a review

A review of mainly the past two years is undertaken of the industrial applications of pulsed power. Repetitively operated pulsed power generators with a moderate peak power have been developed for industrial applications. These generators are reliable and have low maintenance. Development of the pulsed power generators helps promote industrial applications of pulsed power for such things as food processing, medical treatment, water treatment, exhaust gas treatment, ozone generation, engine ignition, ion implantation and others. Here, industrial applications of pulsed power are classified by application for biological effects, for pulsed streamer discharges in gases, for pulsed discharges in liquid or liquid- mixture, and for material processing.

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Industrial Applications of Pulsed Power Technology

This article concerns the foundations of a new technology for surface modification of metallic materials based on the use of original sources of low-energy, high-current electron beams. The sources contain an electron gun with an explosive-emission cathode and a plasma anode, placed in a guide magnetic field. The acceleration gap and the transportation channel are prefilled with plasma with the use of spark plasma sources or a low-pressure reflected discharge. The electron-beam sources produce electron beams with the parameters as follows: electron energy 10–40 keV; pulse duration 0.5–5 μs; energy density 0.5–40 J/cm2, and beam cross-section area 10–50 cm2. They are simple and reliable in operation. Investigations performed with a variety of constructional and tool materials (steels, aluminum and titanium alloys, hard alloys) have shown that the most pronounced changes of the structure-phase state occur in the near-surface layers quenched from the liquid state, where the crystallization front velocity rea...

Pulsed electron-beam technology for surface modification of metallic materials

Laser ablation is a method for fabricating various kinds of nanoparticles including semiconductor quantum dots, carbon nanotubes, nanowires, and core shell nanoparticles. In this method, nanoparticles are generated by nucleation and growth of laser-vaporized species in a background gas. The extremely rapid quenching of vapor is advantageous in producing high purity nanoparticles in the quantum size range (< 10 nm). In this review, the formation mechanism of nanoparticles by laser ablation is summarized. Recent progress on the control of nanoparticle size and the challenges for functional nanoparticle synthesis by advanced laser ablation technology are then discussed.

https://www.jstage.jst.go.jp/article/kona/34/0/34_2017009/_pdf

Synthesis of Nanoparticles by Laser Ablation: A Review

http://www.dmf.unisalento.it/sub-web/leas/Pubblicazioni/COMPARISON%20OF%20NANOSECOND%20LASER%20ABLATION.pdf

Comparison of nanosecond laser ablation at 1064 and 308 nm wavelength

The theory is given of the voltage output of a Rogowski coil excited by a current pulse flowing along the axis of the coil. In this theory the Rogowski coil is considered as a delay line. The results do not differ from those obtained usually by considering the coil as a voltage source dφ/dt with an inductive output impedance. Details are also given of the design of two Rogowski coils and their working modes are fully analyzed.

Rogowski coils: theory and experimental results

We report on the results concerning the characteristics and the behavior of expanding plasma generated by a Laser Ion Source ~LIS!. The LIS technique is an efficient means in producing of multi-charged ions utilizing pulsed laser beams. In order to extract Cu ions, in this experiment an XeCl excimer UV laser was employed, providing a power density on the target surface up to 5 3 10 8 W0cm 2 . Two typologies of diagnostic systems were developed in order to detect the plasma current and the ion energy. The time-of-flight ~TOF! measurements were performed exploiting either a Faraday cup or an Ion Energy Analyzer ~IEA!. This latter allowed getting quantitative information about the relative ion abundances, their kinetic energy and their charge state. To study the plasma characteristics we measured the total etched material per pulse at 70 mJ. It was 0.235 mg and the overall degree of ionization, 16%. The angular distribution of the ablated material was monitored by optical transmission analysis of the deposited film as a function of the angle with respect to the normal to the target surface. Applying a high voltage to an extraction gap a multi-charged ion beam was obtained; different peaks could be distinguished in the TOF spectrum, resulting from the separation of ions of hydrogen, adsorbed compounds in the target and copper.

/pdf/a-study-of-the-parameters-of-particles-ejected-from-a-laser-44zsveok2x.pdf

A study of the parameters of particles ejected from a laser plasma

In this work the experimental results of a nonequilibrium laser-plasma induced by an ultraviolet 308 nm excimer laser are reported. All measurements were performed fixing the laser energy at 70 mJ. It was concentrated on a 0.0099 cm2 spot by a convergent focal lens of 15 cm focal length. The utilized target was a 99.99% pure Cu disk. An 8 cm in diameter movable Faraday cup was developed in order to detect the plasma flow pulse at different positions along a drift tube. Analyzing the time-of-flight pulse under different cup bias voltage, we were able to distinguish the electron pulse, the suprathermal ions, and the thermal evolution of the plasma. In addition, by applying a breakdown voltage as polarizing cup voltage, we characterized the duration of the neutral component. To determine the system particle production efficiency, the total etched material per pulse, 0.235 μg, and the fractional ionization were measured. The expelled particle flux distribution was measured by an optical transmission analysis of a Cu deposited film on a glass substrate. The plasma flow was detected along its propagation axis, between 6 and 40 cm far from the target. The ablation process expelled particles with an initial velocity of 34 km/s, while the maximum ion concentration was 1 μs after the laser pulse. The plasma created propagates with a mean velocity of about 20 km/s. During the propagation, the longitudinal plasma dimension changed from 2.8 cm, near the target, to 31 cm at the maximum cup distance analyzed. At lowest distances, the cup signal wave forms presented a plateau due to the high dense plasma undergone to the space charge regime governed by the Child–Langmuir law.

/pdf/characterization-of-a-nonequilibrium-xecl-laser-plasma-by-a-epyqb8tk3x.pdf

Characterization of a nonequilibrium XeCl laser-plasma by a movable Faraday cup

We present the results concerning the physics of the expanding plasma produced by a laser ion source. An efficient source of multiple charged ions was realized by means of an excimer laser. The analysis of the generated plasma was performed for three different laser spot sizes, determining the threshold conditions of the ablation process for a Cu target. Two typologies of Faraday cups were developed in order to detect the plasma current and the ion current along the propagation tube. The time-of-flight measurements were performed inserting in front of the cup an adjustable voltage electrostatic barrier that allowed us to get quantitative information about the ion flux and the kinetic energy of the produced ions. To study the plasma characteristics we measured the total etched material per pulse, 0.25 μg, and the fractional ionization, 12%. The ablated material distribution was monitored by optical transmission analysis of a deposited film. Applying a high voltage to the extraction gap, an ion beam contain...

Vincenzo Nassisi

Papers

Comparison of nanosecond laser ablation at 1064 and 308 nm wavelength

Rogowski coils: theory and experimental results

A study of the parameters of particles ejected from a laser plasma

Characterization of a nonequilibrium XeCl laser-plasma by a movable Faraday cup

Physics of the expanding plasma ejected from a small spot illumined by an ultraviolet pulsed laser