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In this study, we have investigated carbon ions, fast electrons and gamma-ray energy spectra and the corresponding temperatures when next-generation 10 petawatt (PW) lasers (irradiances of $$5\times 10^{22} \, {\mathrm {W}}\, {\mathrm {cm}}^{-2}$$ ) hit solid targets with a preformed plasma at the front surface. We employed 2D particle-in-cell (PIC) code with the presence of quantum electrodynamics (QED) effects. The maximum energy reached by the accelerated particles, and the corresponding temperature due to nonlinear plasma processes can be affected by varied plasma scale lengths. Here, we show the effects of varied plasma scale lengths on particle acceleration at irradiances on the order of $$10^{22}\,{\mathrm {W}}\,{\mathrm {cm}}^{-2}$$ , which is a new development for laser technology. We have observed that fully ionized carbon ions can reach up to 2.5 GeV energies with an optimum plasma scale length of $$1\, \upmu \hbox {m}$$ and the corresponding temperature of 40 MeV. Accelerated electron energies reach up to 1.5 GeV with the temperatures of 50 MeV for 10 PW laser–plasma interactions with the presence of QED effects. We have demonstrated that by varying plasma scale length, heavy ion energy and temperature can be controlled, which is important for various applications such as hadron therapy and X-ray imaging.

WOS:000460704700031 Perlite mineral contains relatively high water and in general hydrated obsidian forms the perlite which is mainly an amorphous volcanic glass. Photon attenuation properties for different concrete types including natural perlite mineral and B4C have been experimentally investigated by using different radioactive point sources at 81, 276, 303, 356, 384, 662, 1173, 1275 and 1333 keV. SEM and EDAX analyses were carried out to control the crystal structure of the selected concrete types. In this work, HPGe detector based on gamma spectrometer was employed for all experiments. The results revealed that among the prepared concrete samples, the P6 concrete sample has the lowest HVL and MFP values and thus, having best ability to attenuate gamma rays in comparison to the other prepared concretes. Karamanoglu Mehmetbey UniversityKaramanoglu Mehmetbey University [13-M-17, 40-M-16] This work was supported by Karamanoglu Mehmetbey University (Project Numbers: 13-M-17, 40-M-16).

WOS:000668903100003 Abstract: Recent developments of high-power laser systems have enabled the production of high energy proton and electron beams. Here, we studied the laser-driven particle acceleration at near-critical density plasma by employing a 100 TW ultra-fast intense laser pulse through two-dimensional (2D) particle-in-cell (PIC) simulations. The strong magnetic field production and the energy of accelerated particles is numerically demonstrated and shows that there is a dependence on laser focusing position and electron number density. 2D PIC simulation results show that by using 100 TW table-top laser systems, it is possible to produce 120 MeV protons and 250 MeV electrons with a small angular distribution. Graphic abstract: [Figure not available: see fulltext.]. © 2021, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.

In this work, simulations of multipetawatt lasers at irradiances ${\sim }10^{23} \ \mathrm {W}\ \mathrm {cm}^{-2}$ , striking solid targets and implementing two-dimensional particle-in-cell code was used to study particle acceleration. Preformed plasma at the front surface of a solid target increases both the efficiency of particle acceleration and the reached maximum energy by the accelerated charged particles via nonlinear plasma processes. Here, we have investigated the preformed plasma scale length effects on particle acceleration in the presence and absence of nonlinear quantum electrodynamic (QED) effects, including quantum radiation reaction and multiphoton Breit–Wheeler pair production, which become important at irradiances ${\sim } 10^{23}\ \mathrm {W}\ \mathrm {cm}^{-2}$ . Our results show that QED effects help particles gain higher energies with the presence of preformed plasma. In the results for all cases, preplasma leads to more efficient laser absorption and produces more energetic charged particles, as expected. In the case where QED is included, however, physical mechanisms changed and generated secondary particles ( $\gamma$ -rays and positrons) reversing this trend. That is, the hot electrons cool down due to QED effects, while ions gain more energy due to different acceleration methods. It is found that more energetic $\gamma$ -rays and positrons are created with increasing scale length due to high laser conversion efficiency ( ${\sim }$ 24 % for $\gamma$ -rays and $\sim$ 4 % for positrons at $L = 7\ \mathrm {\mu }\textrm {m}$ scale length), which affects the ion and electron acceleration mechanisms. It is also observed that the QED effect reduces the collimation of angular distribution of accelerated ions because the dominant ion acceleration mechanism is changing when QED is involved in the process.

We present results of 2D particle-in-cell (PIC) simulations of carbon ion acceleration by 10 petawatt (PW) laser pulses, studying both circular polarized (CP) and linear polarized (LP) pulses. We carry out a thickness scanning of a solid carbon target to investigate the ideal thickness for carbon ion acceleration mechanisms using a 10 PW laser with an irradiance of 5 × 1022 W cm−2. The energy spectra of carbon ions and electrons and their temperature are studied. Additionally, for the carbon ions, their angular divergence is studied. It is shown that the ideal thickness for the carbon acceleration is 120 nm and the cutoff energy for carbon ions is 5 and 3 GeV for CP and LP pulses, respectively. The corresponding carbon ions temperature is ~1 and ~0.75 GeV. On the other hand, the energy cutoff for the electrons is ~500 MeV with LP and ~400 MeV with CP laser pulses. We report that the breakout afterburner mechanism is most likely causing the acceleration of carbon ions to such high energies for the optimal target thickness.

Yoğunluğu >1020 Wcm-2 seviyesinde olan yüksek güç ve yoğunluktaki lazerler yüksek enerjili x ışınları, γ-ışınları ve nötronlar üretebilmektedir. Ayrıca yüklü parçacıkları yüksek enerjilere hızlandırabilirler ve her türlü nükleer reaksiyonları tetikleyebilmektedirler. Füzyon-Fisyon reaksiyonu senaryosunun temel konsepti, lazer ile hızlandırılmış parçacıkların veya iyon demetlerinin yoğunluğuna dayanır. Füzyon-Fisyon reaksiyon sistemi üretim hedefi ve reaksiyon hedefinden meydana gelmektedir. Bu çalışmada, katı hedefte hızlandırılmış döteron için 2D EPOCH PIC simülasyonları kullanılarak hesaplamalar yapılmıştır. Üretim hedefinde döteronların hızlandırılması için lazer sisteminin 200TW’lık güç, 5J enerji ve 25fs atma süresine sahip olduğu kabul edildi. Bu tarz lazerler hedef üzerinde 10 µm’ye odaklandığı zaman 1020 W cm-2 yoğunluğa çıkabilmektedir. Çalışmamızda gösterilmiştir ki bu tarz masaüstü terawatt lazerler Füzyon-Fisyon reaksiyonları için döteronları 10 MeV enerjiye kadar çıkarılabildiğinden kullanılabilmektedir. Füzyon-Fisyon hedef sisteminin simülasyonu için Monte Carlo kodu MCNPX2.7.0 kullanılmıştır. Üretim hedefinden çıkan hızlandırılmış döteryumlar, reaksiyon hedefinin toryum tabakasında nükleer fisyon reaksiyonlarına neden olmaktadır. Reaksiyon hedefindeki toryum tabakası, füzyon tabakası ve CH2 tabakası yaklaşık 5 µm'lik bir kalınlığa sahiptir.

The transport of hot, relativistic electrons produced by the interaction of an intense petawatt laser pulse with a solid has garnered interest due to its potential application in the development of innovative x-ray sources and ion-acceleration schemes. We report on spatially and temporally resolved measurements of megagauss magnetic fields at the rear of a 50-μm thick plastic target, irradiated by a multi-picosecond petawatt laser pulse at an incident intensity of ~1020 W/cm2. The pump-probe polarimetric measurements with micron-scale spatial resolution reveal the dynamics of the magnetic fields generated by the hot electron distribution at the target rear. An annular magnetic field profile was observed ~5 ps after the interaction, indicating a relatively smooth hot electron distribution at the rear-side of the plastic target. This is contrary to previous time-integrated measurements, which infer that such targets will produce highly structured hot electron transport. We measured large-scale filamentation of the hot electron distribution at the target rear only at later time-scales of ~10 ps, resulting in a commensurate large-scale filamentation of the magnetic field profile. Three-dimensional hybrid simulations corroborate our experimental observations and demonstrate a beam-like hot electron transport at initial time-scales that may be attributed to the local resistivity profile at the target rear.

WOS:000398536200009 The energy spectra of protons generated by ultra-intense (10(20) W cm(-2)) laser interactions with a preformed plasma of scale length measured by shadowgraphy are presented. The effects of the preformed plasma on the proton beam temperature and the number of protons are evaluated. Two-dimensional EPOCH particle-in-cell code simulations of the proton spectra are found to be in agreement with measurements over a range of experimental parameters. Karamanoglu Mehmetbey University ResearchKaramanoglu Mehmetbey University [37-M-16]; UK EPSRCEngineering & Physical Sciences Research Council (EPSRC) [EP/G054950/1, EP/G056803/1, EP/G055165/1, EP/M022463/1] The authors gratefully acknowledge the assistance of laser operations, target preparation and engineering staff at the Central Laser Facility of RAL. Part of the research was supported by Karamanoglu Mehmetbey University Research Project 37-M-16. This work was in part funded by the UK EPSRC grants EP/G054950/1, EP/G056803/1, EP/G055165/1, and EP/M022463/1.

In this study, we have presented proton energy spectra produced by such high irradiance (1020 W/cm2 ) lasers interacting with a pre formed plasma in front of the target and with solid targets without a pre formed plasma. The effects of the target thickness and the generated plasma on the maximum energy and proton numbers are assessed. It is observed that experimentally measured maximum proton energy and number of protons have a dependence on target thickness and preformed plasma scale length produced by prepulse laser with the irradiance of ? 1012 W/cm2 . 2D EPOCH PIC code simulation results of the energy spectra of protons are in a good agreement with measured experimental results. Yapılan bu çalışmada,ultra yogun lazerlerin ( ? 1020 W/cm2 ) farklı kalınlıktaki katı hedeflerle etkileşimi sonucu üretilen protonlar incelenmiştir. Ayrıca ana lazerden önce kullanılan ve younluğu? 1012 W/cm2 seviyesinde olan ikincil lazerle önceden oluşturulmuş plazmaların, üretilen protonların enerji spektrumları üzerindeki etkisi araştırılmıştır. Ana lazer tarafından ateşlenen katı hedeflerin kalınlıgının, üretilen protonların yoğunluğu ve maksimum enerjilerine olan etkisi, ayrıca katı maddelerin ön kısmında (lazerle etkileşimin gerçekleştigi bölge) ikincil lazer tarafından önceden oluşturulan plazmaların hızlandırılan protonlar üzerindeki etkisi çalışılmıştır. 2 boyutlu EPOCH PIC simülasyonlarının sonuçları deneysel verilerin sonuçları ile karşılaştırılmış ve elde edilen bulguları destekledigi gözlemlenmiştir.

K-shell spectra of solid Al excited by petawatt picosecond laser pulses have been investigated at the Vulcan PW facility. Laser pulses of ultrahigh contrast with an energy of 160 J on the target allow studies of interactions between the laser field and solid state matter at 1020 W/cm2. Intense X-ray emission of KK hollow atoms (atoms without n = 1 electrons) from thin aluminum foils is observed from optical laser plasma for the first time. Specifically for 1.5 μm thin foil targets the hollow atom yield dominates the resonance line emission. It is suggested that the hollow atoms are predominantly excited by the impact of X-ray photons generated by radiation friction to fast electron currents in solid-density plasma due to Thomson scattering and bremsstrahlung in the transverse plasma fields. Numerical simulations of Al hollow atom spectra using the ATOMIC code confirm that the impact of keV photons dominates the atom ionization. Our estimates demonstrate that solid-density plasma generated by relativistic optical laser pulses provide the source of a polychromatic keV range X-ray field of 1018 W/cm2 intensity, and allows the study of excited matter in the radiation-dominated regime. High-resolution X-ray spectroscopy of hollow atom radiation is found to be a powerful tool to study the properties of high-energy density plasma created by intense X-ray radiation.

WOS:000373585800006 PubMed:27176413 An analysis of an electron spectrometer used to characterize fast electrons generated by ultraintense (10(20) W cm(-2)) laser interaction with a preformed plasma of scale length measured by shadowgraphy is presented. The effects of fringing magnetic fields on the electron spectral measurements and the accuracy of density scale-length measurements are evaluated. 2D EPOCH PIC code simulations are found to be in agreement with measurements of the electron energy spectra showing that laser filamentation in plasma preformed by a prepulse is important with longer plasma scale lengths (> 8 mu m). RFBR Research Project [15-32-21121]; RAS Presidium Program for Basic Research [13]; UK EPSRCEngineering & Physical Sciences Research Council (EPSRC) [EP/G054950/1, EP/G056803/1, EP/G055165/1, EP/M022463/1]; Engineering and Physical Sciences Research CouncilEngineering & Physical Sciences Research Council (EPSRC) [EP/M022463/1, EP/G056803/1] The authors gratefully acknowledge the assistance of laser operations, target preparation, and engineering staff at the Central Laser Facility of RAL. Part of the research was supported by RFBR Research Project No. 15-32-21121 and RAS Presidium Program for Basic Research No. 13. This work was in part funded by the UK EPSRC Grants No. EP/G054950/1, No. EP/G056803/1, No. EP/G055165/1, and No. EP/M022463/1.

Extreme ultra-violet (EUV) laboratory lasers can be used to probe energy transport in laser irradiated solid targets. We report on a recent experiment undertaken at LASERIX whereby the heating of laser-irradiated targets containing a thin layer of iron (50 nm) encased in plastic (CH) was diagnosed using EUV laser (13.9 nm) back-lighter probing. The heating laser pulse duration was 35fs with focal irradiances of \(3 \times 10^{16}\)Wcm\(^{-2}\) and a deliberate prepulse 20 ps before the main pulse at irradiances of \(3 \times 10^{15}\)Wcm\(^{-2}\). A one dimensional hydrodynamic fluid code HYADES has been used to simulate the temporal variation in EUV transmission using IMP opacity values for the iron layer and the simulated transmissions compared to measured transmission values. When a deliberate prepulse is used to preform an expanding plastic plasma, it is found that radiation heating is dominant in the heating of the iron layer giving rise to a rapid decrease in EUV opacity and an increase in the transmission of the 13.9nm laser radiation as the iron ionizes to Fe\(^{5+}\) and above.

X-ray emission from hollow ions offers new diagnostic opportunities for dense, strongly coupled plasma. We present extended modeling of the x-ray emission spectrum reported by Colgan et al. [Phys. Rev. Lett. 110, 125001 (2013)] based on two collisional-radiative codes: the hybrid-structure Spectroscopic Collisional-Radiative Atomic Model (SCRAM) and the mixed-unresolved transition arrays (MUTA) ATOMIC model. We show that both accuracy and completeness in the modeled energy level structure are critical for reliable diagnostics, investigate how emission changes with different treatments of ionization potential depression, and discuss two approaches to handling the extensive structure required for hollow-ion models with many multiply excited configurations.

The potential for coherent extreme ultra-violet (EUV) light in probing laser-produced plasmas is investigated. New results are presented to demonstrate that EUV radiation can be employed to measure heat penetration into solid targets from electrons using the signature of a change of opacity due to heating. We examine, in particular, the effects of hot electron heating of targets. In addition, phase variations after transmission through a laser-irradiated target change the subsequent propagation of the radiation, suggesting a simple diagnostic measuring the far-field footprint of coherent EUV radiation can be a useful measurement of the uniformity of target heating.

We demonstrate the use of extreme ultra-violet (EUV) laboratory lasers in probing energy transport in laser irradiated solid targets. EUV transmission through targets containing a thin layer of iron (50 nm) encased in plastic (CH) after irradiation by a short pulse (35 fs) laser focussed to irradiances 3 × 1016 Wcm−2 is measured. Heating of the iron layer gives rise to a rapid decrease in EUV opacity and an increase in the transmission of the 13.9 nm laser radiation as the iron ionizes to Fe5+ and above where the ion ionisation energy is greater than the EUV probe photon energy (89 eV). A one dimensional hydrodynamic fluid code HYADES has been used to simulate the temporal variation in EUV transmission (wavelength 13.9 nm) using IMP opacity values for the iron layer and the simulated transmissions are compared to measured transmission values. When a deliberate pre-pulse is used to preform an expanding plastic plasma, it is found that radiation is important in the heating of the iron layer while for pre-pu...

Hot electron generation plays an important role in the fast ignition approach to inertial confinement fusion (ICF) and other applications with ultra-intense lasers. Hot electrons of temperature up to 10–20 MeV have been produced by high contrast picosecond duration laser pulses focussed to intensities of ∼1020 W cm−2 with a deliberate pre-pulse on solid targets using the Vulcan Petawatt Laser facility. We present measurements of the number and temperature of hot electrons obtained using an electron spectrometer. The results are correlated to the density scale length of the plasma produced by a controlled pre-pulse measured using an optical probe diagnostic. 1D simulations predict electron temperature variations with plasma density scale length in agreement with the experiment at shorter plasma scale lengths (