A laser parameter study on enhancing proton generation from microtube foil targets

The interaction of an intense laser with a solid foil target can drive [Formula: see text] TV/m electric fields, accelerating ions to MeV energies. In this study, we experimentally observe that structured targets can dramatically enhance proton acceleration in the target normal sheath acceleration regime. At the Texas Petawatt Laser facility, we compared proton acceleration from a [Formula: see text] flat Ag foil, to a fixed microtube structure 3D printed on the front side of the same foil type. A pulse length (140-450 fs) and intensity ((4-10) [Formula: see text] W/cm[Formula: see text]) study found an optimum laser configuration (140 fs, 4 [Formula: see text] W/cm[Formula: see text]), in which microtube targets increase the proton cutoff energy by 50% and the yield of highly energetic protons ([Formula: see text] MeV) by a factor of 8[Formula: see text]. When the laser intensity reaches [Formula: see text] W/cm[Formula: see text], the prepulse shutters the microtubes with an overcritical plasma, damping their performance. 2D particle-in-cell simulations are performed, with and without the preplasma profile imported, to better understand the coupling of laser energy to the microtube targets. The simulations are in qualitative agreement with the experimental results, and show that the prepulse is necessary to account for when the laser intensity is sufficiently high

Proof-of-principle Experiment on the dynamic Shell formation Concept on the OMEGA Laser

A dynamic shell implosion concept in direct-drive inertial confinement fusion utilizes a spherical pellet of liquid DT, which is first compressed by convergent shocks, then expands after bouncing these shocks from the center, decelerates and forms a shell with the help of following subsequent converged shocks, and finally, implodes resulting in conventional central hot-spot ignition [V. N. Goncharov et al., Phys. Rev. Lett. 125, 065001 (2020)]. Proof-of-principle experiments on the OMEGA laser were proposed to demonstrate, for the first time, the feasibility of dynamic formation of a dense shell in a spherically expanding cloud of plasma. This shell is formed by convergent shocks launched at the edge of the cloud, with the cloud itself formed as a result of compression and relaxation of a plastic-foam ball target. The results of experiments are expected to be reported and compared with 2-D and 3-D radiation-hydrodynamic simulations. These simulations predict good stability of the dynamic shells considered to low-mode asymmetries induced by laser-illumination nonuniformities, target offset, and stalk mount. *This material is based upon work supported by the Department of Energy National NuclearSecurity Administration under Award Number DE-NA0003856 and ARPA-E BETHE Grant No.DE-FOA-0002212. The experiment was conducted at the Omega Laser Facility at the Universityof Rochester’s Laboratory for Laser Energetics with the beam time through the NationalLaser Users’ Facility (NLUF) program

From hybrid peace to human security: rethinking EU strategy toward conflict. The Berlin report of the Human Security Study Group presented to High Representative of the Union for Foreign Affairs & Security Policy Federica Mogherini

This report proposes that the European Union adopts a second generation human security approach to conflicts, as an alternative to Geo-Politics or the War on Terror. Second generation human security takes forward the principles of human security and adapts them to 21st century realities. The report argues that the EU is a new type of 21st century political institution in contrast to 20th century nation-states. Twentieth-century nation states were based on a clear distinction between inside and outside. Typical outside instruments were state-to-state diplomacy or economic and military coercion. Typical inside instruments are the rule of law, politics, and policing. In today’s complex, contested and connected world, outside instruments do not work; they backfire and make things worse. Human security is about extending the inside beyond the EU. Hybrid Peace is what happens when 20th century peace-making is applied in contemporary conflicts. Contemporary conflicts have to be understood not as Clausewitzean contests of will between two sides with legitimate goals but as a sort of predatory social condition in which networks of armed groups instrumentalise extremists identities and enrich themselves through violence. Up to now, the EU has focussed on top-down peace-making, humanitarian assistance and post-conflict reconstruction. These policies can easily be subverted because they can end up entrenching criminalised extremist networks. Second generation human security is about establishing legitimate political authority and legitimate livelihoods to counter this predatory social condition. It encompasses multi-layer, incremental and inclusive peace processes with particular emphasis on support for local ceasefires and civil society; security assistance in establishing safe areas and safe corridors and protecting individuals and their communities; economic measures including justice to undercut the illegal economy. Second generation human security involves continuous engagement so as to combine prevention, early warning, crisis response and reconstruction as intertwined activities, and places emphasis on gender so as to oppose the extreme gender relations that are constructed in contemporary wars. The instruments of second generation human security include: Creative diplomacy at all levels including smart multilateralism An emphasis on justice across the entire spectrum of abuse and criminality prevalent in today’s conflicts The use of smart sanctions where they involve engagement with civil society, impact monitoring, and compliance with international law Conditionality aimed at countering predation, corruption, sectarianism and impunity rather than introducing neo-liberal reforms Civilian-led missions that include some combination of humanitarian workers, human rights monitors, legal experts, police and where needed military forces, and that involve both men and wome