Ignition Delay Times of Kerosene (Jet-A)/Air Mixtures

Ignition of Jet-A/air mixtures was studied behind reflected shock waves. Heating of shock tube at temperature of 150 C was used to prepare a homogeneous fuel mixture. Ignition delay times were measured from OH emission at 309 nm and from absorption of He-Ne laser radiation at 3.3922 micrometers. The conditions behind shock waves were calculated by one-dimensional shock wave theory from initial conditions T1, P1, mixture composition and incident shock wave velocity. The ignition delay times were obtained at two fixed pressures 10, 20 atm for lean, stoichiometric and rich mixtures (ER=0.5, 1, 2) at an overall temperature range of 1040-1380 K.Comment: V.P. Zhukov, V.A. Sechenov, and A.Yu. Starikovskii, Ignition Delay Times of Kerosene(Jet-A)/Air Mixtures, 31st Symposium on Combustion, Heidelberg, Germany, August 6-11, 200

Influence of misalignments on performance of externally occulted solar coronagraphs. Application to PROBA-3/ASPIICS

ASPIICS is a novel externally occulted coronagraph that will be launched onboard the PROBA-3 mission of ESA. The external occulter (EO) will be placed on one satellite ~150 m ahead of the second satellite with an optical instrument. During part of each orbit, the satellites will fly in a precise formation, constituting a giant externally occulted coronagraph. Large distance between the EO and the primary objective will allow observations of the white-light solar corona starting already from ~1.1RSun. We analyze influence of shifts of the satellites and misalignments of optical elements on diffracted light. Based on the quantitative influence of misalignments on diffracted light, we will provide a "recipe" for choosing the size of the internal occulter (IO) to achieve a trade-off between the minimal height of observations and sustainability to possible misalignments. We implement a numerical model of the diffracted light and its propagation through the optical system, and compute intensities of diffracted light throughout the instrument. Our numerical model extends axi-symmetrical model of Rougeot et al. 2017 to non-symmetrical cases. The computations fully confirm main properties of the diffracted light obtained from semi-analytical consideration. Results: relative influences of various misalignments are significantly different. We show that: the IO with R=1.1RSun is large enough to compensate possible misalignments in ASPIICS, apodizing the edge of the IO leads to additional suppression of the diffracted light. Conclusions: the most important misalignment is the tilt of the telescope WRT the line connecting the center of the EO and the entrance aperture. Special care should be taken to co-align the EO and the coronagraph, i.e. co-aligning the diffraction fringe from the EO and the IO. We suggest that the best orientation strategy is to point the coronagraph to the center of the EO.Comment: 13 pages, 15 figure

Investigations of local electronic transport in InAs nanowires by scanning gate microscopy at helium temperatures

In the current paper a set of experiments dedicated to investigations of local electronic transport in undoped InAs nanowires at helium temperatures in the presence of a charged atomic-force microscope tip is presented. Both nanowires without defects and with internal tunneling barriers were studied. The measurements were performed at various carrier concentrations in the systems and opacity of contact-to-wire interfaces. The regime of Coulomb blockade is investigated in detail including negative differential conductivity of the whole system. The situation with open contacts with one tunneling barrier and undivided wire is also addressed. Special attention is devoted to recently observed quasi-periodic standing waves.Comment: 7 pages, 4 figures. arXiv admin note: text overlap with arXiv:1309.325

Correlations of mutual positions of charge density waves nodes in side-by-side placed InAs wires measured with scanning gate microscopy

We investigate the correlations of mutual positions of charge density waves nodes in side-by-side placed InAs nanowires in presence of a conductive atomic force microscope tip served as a mobile gate at helium temperatures. Scanning gate microscopy scans demonstrate mutual correlation of positions of charge density waves nodes of two wires. A general mutual shift of the nodes positions and "crystal lattice mismatch" defect were observed. These observations demonstrate the crucial role of Coulomb interaction in formation of charge density waves in InAs nanowires