Optimizing laser coupling,matter heating,and particle acceleration from solids using multiplexed ultraintense lasers

Realizing the full potential of ultrahigh-intensity lasers for particle and radiation generation will require multi-beam arrangements due to technology limitations.Here,we investigate how to optimize their coupling with solid targets.Experimentally,we show that overlapping two intense lasers in a mirror-like configuration onto a solid with a large preplasma can greatly improve the generation of hot electrons at the target front and ion acceleration at the target backside.The underlying mechanisms are analyzed through multidimensional particle-in-cell simulations,revealing that the self-induced magnetic fields driven by the two laser beams at the target front are susceptible to reconnection,which is one possible mechanism to boost electron energization.In addition,the resistive magnetic field generated during the transport of the hot electrons in the target bulk tends to improve their collimation.Our simulations also indicate that such effects can be further enhanced by overlapping more than two laser beams.

The association of type and number of high-risk criteria with cancer-specific mortality in prostate cancer patients treated with radical prostatectomy

Objectives:This study aimed to test the association between of type and number of D'Amico high-risk criteria(DHRCs)with cancer-specific mortality(CSM)in high-risk prostate cancer patients treated with radical prostatectomy.Materials and methods:In the Surveillance,Epidemiology,and End Results database(2004–2016),we identified 31,281 radical prostatectomy patients with at least 1 DHRC,namely,prostate-specific antigen(PSA)>20 ng/mL(hrPSA),biopsy Gleason Grade Group(hrGGG)score of 4 and 5,or clinical tumor stage≥T3(hrcT).Multivariable Cox regression models and competing risks regression models(adjusting for other cause mortality)tested the association between DHRCs and 5-year CSM.Results:Of 31,281 patients,14,394(67%)exclusively harbored hrGGG,3189(15%)harbored hrPSA,and 1781(8.2%)harbored hrcT.Only 2132 patients(6.8%)harbored a combination of the 2 DHRCs,and 138(0.6%)had all 3 DHRCs.Five-year CSMrates ranged from 0.9%to 3.0%when any individual DHRC was present(hrcT,hrPSA,and hrGGG,in that order),1.6%to 5.9%when 2 DHRCs were present(hrPSA-hrcT,hrcT-hrGGG,and hrPSA-hrGGG,in that order),and 8.1%when all 3 DHRCs were present.Cox regression models and competing risks regression confirmed the independent predictor status of DHRCs for 5-year CSM that was observed in univariable analyses,with hazard ratios from 1.00 to 2.83 for 1 DHRC,2.35 to 5.88 for combinations of 2 DHRCs,and 7.13 for all 3 DHRCs.Conclusions:Within individual DHRCs,hrcT and hrPSA exhibited weaker effects than hrGGG did.Moreover,a dose-response effect was identified according to the number of DHRCs.Accordingly,the type and number of DHRCs allow further risk stratification within the high-risk subgroup.

Innovative Education and Training in high power laser plasmas(PowerLaPs) for plasma physics, high power laser-matter interactions and high energy density physics-theory and experiments

The Erasmus Plus programme’Innovative Education and Training in high power laser plasmas’,otherwise known as PowerLaPs,is described.The PowerLaPs programme employs an innovative paradigm in that it is a multi-centre programme where teaching takes place in five separate institutes with a range of different aims and styles of delivery.The ’in class’ time is limited to four weeks a year,and the programme spans two years.PowerLaPs aims to train students from across Europe in theoretical,applied and laboratory skills relevant to the pursuit of research in laserplasma interaction physics and inertial confinement fusion(ICF).Lectures are intermingled with laboratory sessions and continuous assessment activities.The programme,which is led by workers from the Technological Educational Institute(TEI)of Crete,and supported by co-workers from the Queen’s University Belfast,the University of Bordeaux,the Czech Technical-University in Prague,Ecole Polytechnique,the University of Ioannina,the University of Salamanca and the University of York,has just completed its first year.Thus far three Learning Teaching Training(LTT)activities have been held,at the Queen’s University Belfast,the University of Bordeaux and the Centre for Plasma Physics and Lasers(CPPL)of TEI Crete.The last of these was a two-week long Intensive Programme(IP),while the activities at the other two universities were each five days in length.Thus far work has concentrated upon training in both theoretical and experimental work in plasma physics,high power laser-matter interactions and high energy density physics.The nature of the programme will be described in detail and some metrics relating to the activities carried out to date will be presented.

Influence of laser polarization on collective electron dynamics in ultraintense laser-foil interactions

The collective response of electrons in an ultrathin foil target irradiated by an ultraintense(~6×10^(20)W cm^(-2)) laser pulse is investigated experimentally and via 3D particle-in-cell simulations. It is shown that if the target is sufficiently thin that the laser induces significant radiation pressure, but not thin enough to become relativistically transparent to the laser light, the resulting relativistic electron beam is elliptical, with the major axis of the ellipse directed along the laser polarization axis. When the target thickness is decreased such that it becomes relativistically transparent early in the interaction with the laser pulse, diffraction of the transmitted laser light occurs through a so called ‘relativistic plasma aperture', inducing structure in the spatial-intensity profile of the beam of energetic electrons. It is shown that the electron beam profile can be modified by variation of the target thickness and degree of ellipticity in the laser polarization.