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We discuss the progress in the development of extreme light sources that will open new horizons for studying a wide range of fundamental science and astrophysics problems. The regimes of dominant radiation reaction, which completely change the electromagnetic wave?matter interaction, will be revealed, resulting in a new extremely powerful source of ultrashort high-brightness gamma-ray pulses. The possibility of abundant electron?positron pair creation via multi-photon processes and the possibility of reaching the critical field of quantum electrodynamics, which would lead to vacuum polarization and breakdown, are attracting considerable attention.

Kα line emissions from Mo and Ag plates were experimentally studied using clean, ultrahigh-intensity femtosecond laser pulses. The absolute yields of Kα x-rays at 17 keV from Mo and 22 keV from Ag were measured as a function of the laser pulse contrast ratio and irradiation intensity. Significantly enhanced Kα yields were obtained for both Mo and Ag by employing high contrast ratios and irradiances. Conversion efficiencies of 4.28 × 10−5 /sr for Mo and 4.84 × 10−5 /sr for Ag, the highest values obtained to date, were demonstrated with contrast ratios in the range 10−10 to 10−11.

In order to obtain the angular dependent electron energy distributions, we developed a multichannel electron spectrometer (MCESM) with high energy and angular resolutions. The MCESM consists of seven small electron spectrometers set in every 5° on the basement, each of which detection range is up to 25 MeV. In the experiment, we successfully obtained electron spectra from imploded cone-shell target as well as gold plane target irradiated by ultraintense (300 J/5 ps) laser beam.

A laser ion source (LIS) can easily provide a high current beam. However, it has been difficult to obtain a longer beam pulse while keeping a high current. On occasion, longer beam pulses are required by certain applications. For example, more than 10 micros of beam pulse is required for injecting highly charged beams to a large sized synchrotron. To extend beam pulse width, a solenoid field was applied at the drift space of the LIS at Brookhaven National Laboratory. The solenoid field suppressed the diverging angle of the expanding plasma and the beam pulse was widened. Also, it was observed that the plasma state was conserved after passing through a few hundred gauss of the 480 mm length solenoid field.

Laser plasma interactions in a relativistic regime relevant to the fast ignition in inertial confinement fusion have been investigated. Ultraintense laser propagation in preformed plasmas and hot electron generation are studied. The experiments are performed using a 100 TW 0.6 ps laser and a 20 TW 0.6 ps laser synchronized by a long pulse laser. In the study, a self-focused ultraintense laser beam propagates along its axis into an overdense plasma with peak density 1022/cm3. Channel formation in the plasma is observed. The laser transmission in the overdense plasma depends on the position of its focus and can take place in plasmas with peak densities as high as 5×1022/cm3. The hot electron beams produced by the laser-plasma interaction have a divergence angle of ∼30°, which is smaller than that from laser-solid interactions. For deeper penetration of the laser light into the plasma, the use of multiple short pulse lasers is proposed. The latter scheme is investigated using particle-in-cell simulation. It ...

A study on electro-magnetically driven shock in laboratory experiments is reported. The shock waves are driven by a compact pulse device at 40 km/s into a high-Z gas with 1 μg/cm3. The pulse power device with tapered electrodes can generate a quasi steady and one-dimensional shock. Ion-electron and ionization relaxation processes, based on a steady and 1-Dimensional shock condition, are calculated. Comparison of the experimental result to calculation one indicates that the shocks produced by the pulse power device have potential to observe ion-electron and ionization relaxation layer with an appropriate spatial scale.

Hugoniot data of diamond was obtained using laser-driven shock waves in the terapascal range of 0.5–2TPa. Strong shock waves were generated by direct irradiation of a 2.5ns laser pulse on an Al driver plate. The shock wave velocities in diamond and Al were determined from optical measurements. Particle velocities and pressures were obtained using an impedance matching method and known Al Hugoniot. The obtained Hugoniot data of diamond does not show a marked difference from the extrapolations of the Pavlovskii Hugoniot data in the TPa range within experimental errors.

A compact pulse power device is proposed for generation of one-dimensional strong shock waves, and preliminary experimental results are reported. The cross section of the discharge area is decreased by tapered electrodes to prevent the decay of the shock wave. This new device drives a quasi-one-dimensional strong shock with the front speed 45km∕s in the acrylic guiding tube filled with Xe gas. When the front speed is more than the critical speed Drad, an interesting structure is observed at the shock front, which indicates that the radiative energy transport affects the shock structure.

The dependence on laser intensity and pulse duration in energetic proton acceleration by irradiation of ultrashort laser pulses on a 5μm thick copper tape target was measured. The laser intensity was varied from 8.5×1017W∕cm2 to 1.1×1019W∕cm2, and the pulse duration from 55 fs to 400 fs. The maximum proton energy increased as the pulse duration was increased while the laser intensity was kept constant. The dependence of the maximum proton energy on laser intensity and pulse duration was in good agreement with an analytical plasma-expanding model.

In continuation of the collaborative work between the Institute of Laser Engineering, Osaka and Max–Planck‐Institut fur Quantenoptik, Garching on x‐ray confining cavities, we have performed a new series of experiments using the GEKKO‐XII laser facility (4 kJ, 0.9 ns, λ=0.35 μm). The results from two experimental objectives will be presented. The first objective was the direct observation of the x‐ray confinement effect in a cavity. A special design target allowed the simultaneous measurement of the x‐ray flux emanating from a ‘‘closed’’ cavity and an ‘‘open’’ cavity. The second objective was the study of radiation transport mechanism in high‐ and low‐Z materials. Thin foils of Au and Al were used as windows on diagnostic holes of x‐ray confining cavities and their emission was compared to that of an open hole. A summary of the main results will be presented.

In order to measure the amounts of fluorine (F) atoms in the off-gas drain from polymer electrolyte fuel cells (PEFCs) using proton Rutherford Backscattering Spectroscopy (p-RBS), we used an impinger where potassium hydroxide (KOH) solution (0.1 mol/L) was filled and prepared the targets for p-RBS using these samples. In the measured RBS spectrum, however, the peak of fluorine (F) atoms of the decomposition products could not be clearly observed due to the interference by the low energy tail of the potassium (K) atom's peak. We confirmed using SEM, EPMA and XRD that the origin of the low energy tail of the potassium (K) atom's peak was the absorption of carbon dioxide (CO 2 ) in the air by potassium hydroxide (KOH) solution during drying. We also found that the target prepared by vacuum drying was more suitable for measuring the spectra of light elements in p-RBS than that by natural drying.

We present the new regime of high-order harmonics generation by multi-TW femtosecond lasers irradiating gas jet targets. We describe new results concerning the off-axis XUV harmonics emission, angular distribution and source size.

The International Fusion Materials Irradiation Facility (IFMIF), presently in its Engineering Validation and Engineering Design Activities (EVEDA) phase under the frame of the Broader Approach Agreement between Europe and Japan, accomplished in summer 2013, on schedule, its EDA phase with the release of the engineering design report of the IFMIF plant, which is here described. Many improvements of the design from former phases are implemented, particularly a reduction of beam losses and operational costs thanks to the superconducting accelerator concept, the re-location of the quench tank outside the test cell (TC) with a reduction of tritium inventory and a simplification on its replacement in case of failure, the separation of the irradiation modules from the shielding block gaining irradiation flexibility and enhancement of the remote handling equipment reliability and cost reduction, and the water cooling of the liner and biological shielding of the TC, enhancing the efficiency and economy of the related sub-systems. In addition, the maintenance strategy has been modified to allow a shorter yearly stop of the irradiation operations and a more careful management of the irradiated samples. The design of the IFMIF plant is intimately linked with the EVA phase carried out since the entry into force of IFMIF/EVEDA in June 2007. These last activities and their on-going accomplishment have been thoroughly described elsewhere (Knaster J et al [19]), which, combined with the present paper, allows a clear understanding of the maturity of the European-Japanese international efforts. This released IFMIF Intermediate Engineering Design Report (IIEDR), which could be complemented if required concurrently with the outcome of the on-going EVA, will allow decision making on its construction and/or serve as the basis for the definition of the next step, aligned with the evolving needs of our fusion community. © 2015 IAEA, Vienna.

Helix-helix interactions in lipid bilayers are principal processes that determine the folding, oligomerization, and conformational change of helical transmembrane proteins. Not only the amino acid sequence of the protein but also the composition of surrounding lipids significantly affect the stability of the interaction. The GXXXG motif is frequently found at interaction interface of the transmembrane region, and proposed to mediate helix associations via hydrogen bonding between Cα-H donor and the backbone C=O acceptor. However, energetic/kinetic contributions of the motif have not been well characterized.In this study, we investigated the effect of a GXXXG-motif introduced into the center of the host transmembrane helix (AALALAA)3, examined by a single molecule FRET technique. The host helices are known to weakly self-associate in antiparallel orientations in POPC vesicles. In contrast, the GXXXG motif significantly stabilized a parallel association of the helices with lifetimes of subseconds. We also found that cholesterol suppressed the GXXXG-mediated parallel associations, demonstrating the importance of lipid environment on the helix-helix interaction