Direct observations of magnetic-field-aligned (parallel) electric fields in the downward current region of the aurora provide decisive evidence of naturally occurring double layers. We report measurements of parallel electric fields, electron fluxes and ion fluxes related to double layers that are responsible for particle acceleration. The observations suggest that parallel electric fields orga...

Previous systems for measuring cross-correlated light scattering by small particles suspended in a liquid with multiple-scattering suppression have illuminated the particles with two laser beams. It is shown that multiple-scattering suppression should also occur in cross correlation for a system that employs a single laser beam and two closely spaced detectors with wide fields of view. The sing...

Measuring electron-beam sizes is very important to estimate horizontal and vertical emittances in lowemittance rings. The beam size monitor using Fresnel zone plates (FZPs) has been designed for the Super-SOR ring (a new name of the VSX ring), which is a thirdgeneration synchrotron light source being planned by the University of Tokyo. The monitor system has a structure of a long-distance x-ray...

The using of double heat pipe based heat exchanger (HPHX) in a conventional fully fresh air air-conditioning (AC) system was examined in the present study. The fabricated HPHXs were tested under the actual conditions and the measured data were used to study the performance of the existing AC system (System A) and AC system equipped with the double HPHX (System B) for a yearly operation through ...

Physically speaking, the delta function like beam-beam nonlinear forces at interaction points (IPs) act as a sum of delta function nonlinear multipoles. By applying the general theory established in ref. [1], in this paper we investigate analytically the beam-beam interaction limited dynamic apertures and the corresponding beam lifetimes for both the round and the flat beams. Relations between ...

in this paper, chaotic motion analysis and its control for a non-planar non-linear cantilever beam with axial and lateral parametric excitation in the free end is accomplished. this is a new method for control of chaotic motion of a non-linear planar beam. in this survey, internal resonance of the beam is 2:1 and the initial resonance is in the outside of plane and it is assumed a sub-resonance...

A polarized neutron set-up is proposed with a focusing curved mirror system to increase the intensity and to obtain an electronically adjustable energy and energy resolution. The set-up consists of 3 curved neutron mirror systems with 2 Drabkin monochromators in between. The 3 mirror systems, necessary to optimize such a double Drabkin monochromator, in addition focus the neutron beam in 2 dire...

The detection of a gold nanoparticle contrast agent is demonstrated using a photothermal modulation technique and phase sensitive optical coherence tomography (OCT). A focused beam from a laser diode at 808 nm is modulated at frequencies of 500 Hz-60 kHz while irradiating a solution containing nanoshells. Because the nanoshells are designed to have a high absorption coefficient at 808 nm, the l...

A new bunch-by-bunch beam position measurement (BPM) prototype has been designed and built to monitor the beam instability and analyse the beam trip in the BEPCII (Beijing Electron-Positron ColliderII) machine. The broadband electronics system which employs fast analogy digital converter (ADC) and field programmable gate array (FPGA) can obtain the beam information bunch-by-bunch with high bunc...

background: one of the main problems of dedicated iort accelerators is to determine dosimetric characteristics of the electron beams. monte carlo simulation of iort accelerator head and produced beam will be useful to improve the accuracy of beam dosimetry. materials and methods: liac accelerator head was modeled using the beamnrcmonte carlo simulation system. phase-space files were generated a...