Recent Advances in Design of Low Cost Film Concentrator and Low Pressure Free Piston Stirling Engines for Solar Power

The free piston Stirling-linear alternator was shown to be scalable to power levels of tens of kilowatts in a form which is simple, efficient, long lived and relatively inexpensive. It avoids entirely the vexing problem of high pressure shaft, and its control requirements are not severe nor do they represent a significant threat to durability. Linear alternators have demonstrated high efficiency and moderate weight, and are capable of delivering 3 phase power from single machines without great increases of cost or complexity. There remains no apparent impediments to the commercial exploitation of the free piston engine for solar electric power generation

Paraboloidsysteme

SIGLETIB Hannover: DR 4724 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Electron trapping and reinjection in prepulse-shaped gas targets for laser-plasma accelerators

A novel mechanism for injection, emittance selection, and postacceleration for laser wakefield electron acceleration is identified and described. It is shown that a laser prepulse can create an ionized plasma filament through multiphoton ionization and this heats the electrons and ions, driving an ellipsoidal blast-wave aligned with the laser-axis. The subsequent high-intensity laser-pulse generates a plasma wakefield which, on entering the leading edge of the blast-wave structure, encounters a sharp reduction in electron density, causing density down-ramp electron injection. The injected electrons are accelerated to ∼2  MeV within the blast-wave. After the main laser-pulse has propagated past the blast-wave, it drives a secondary wakefield within the homogenous background plasma. On exiting the blast-wave structure, the preaccelerated electrons encounter these secondary wakefields, are retrapped, and accelerated to higher energies. Due to the longitudinal extent of the blast-wave, only those electrons with small transverse velocity are retrapped, leading to the potential for the generation of electron bunches with reduced transverse size and emittance

Specialised gas targets for controlled injection of electrons into laser-driven wakefields.

Laser-driven wakefield acceleration within capillary discharge waveguides has been used to generate high quality electron bunches with GeV scale energies. However, uncontrolled self-injection by wave-breaking of non-linear plasma waves can lead to large fluctuations in energy spread, divergence and charge of the accelerated bunches. Specialised plasma targets with tailored density profiles offer the possibility to overcome these issues by controlling the injection and acceleration process. This requires precise manipulation of the longitudinal density profile. Therefore we developed plasma targets based on a capillary structure with multiple gas in- and outlets operated at steady-state gas flow. Here we give a detailed overview of the target concept and discuss preliminary experimental results for ionisation injection obtained by utilising these targets at the ASTRA laser at Rutherford Appleton Lab

Kernstruktur bei hohen Drehimpulsen. Messung hochenergetischer Myonen aus kosmischen Schauern (KASKADE). n"+-Kontaktierung bei HP-Ge-Detektoren Wissenschaftlicher Schlussbericht

Available from TIB Hannover: F96B660+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

In-beam investigation and the structure of states in "1"1"3Sn

The results of in-beam investigations of "1"1"3Sn using the (p,n), (p,3n), (#alpha#,n) and (#alpha#,2n) reactions are summarized. Excited states have been identified until E_x=4715 MeV and J"#pi#=(27/2"-). For a large number of levels mean lifetimes #tau# have been determined with the DSA method. For the J"#pi#=25/2"+ state at E_x=4059 MeV, #tau#=1.0(4) ns has been measured with the #gamma#-RF method. The experimental results are compared with the predictions of shell-model calculations. Most of the positive-parity states may be considered as one- or three-quasiparticle neutron excitations of the 2d_5_/_2, 1g_7_/_2, 3s_1_/_2 and 2d_3_/_2 shells, the negative-parity states as the coupling of one 1h_1_1_/_2 neutron to the two- or four-quasiparticle neutron excitations in the even-mass "1"1"2Sn core. For the 25/2"+ isomer the three-quasiparticle neutron configuration #nu#(h"2_1_1_/_2g"-"1_7_/_2) has been proposed on the basis of a shell-model analysis using the mass formula formalism. The experimentally observed yrast states in _5_0"1"1"3Sn_6_3 are compared with the corresponding states in the valence-mirror nucleus _6_3"1"4"5Eu_8_2 giving remarkable similarities although the parameters for the shell-model calculations differ considerably. The analysis of nearest-neighbour spacing distributions of 5/2"+ states in "1"1"3Sn does not allow definite conclusions about regularity or chaos. (orig.)59 refs.Available from TIB Hannover: RR 1847(95) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman