An hourglass model for the flare of HST-1 in M87

To explain the multi-wavelength light curves (from radio to X-ray) of HST-1 in the M87 jet, we propose an hourglass model that is a modified two-zone system of Tavecchio & Ghisellini (hereafter TG08): a slow hourglass-shaped or Laval nozzle-shaped layer connected by two revolving exponential surfaces surrounding a fast spine, through which plasma blobs flow. Based on the conservation of magnetic flux, the magnetic field changes along the axis of the hourglass. We adopt the result of TG08---the high-energy emission from GeV to TeV can be produced through inverse Compton by the two-zone system, and the photons from radio to X-ray are mainly radiated by the fast inner zone system. Here, we only discuss the light curves of the fast inner blob from radio to X-ray. When a compressible blob travels down the axis of the first bulb in the hourglass, because of magnetic flux conservation, its cross section experiences an adiabatic compression process, which results in particle acceleration and the brightening of HST-1. When the blob moves into the second bulb of the hourglass, because of magnetic flux conservation, the dimming of the knot occurs along with an adiabatic expansion of its cross section. A similar broken exponential function could fit the TeV peaks in M87, which may imply a correlation between the TeV flares of M87 and the light curves from radio to X-ray in HST-1. The Very Large Array (VLA) 22 GHz radio light curve of HST-1 verifies our prediction based on the model fit to the main peak of the VLA 15 GHz radio light curve.Comment: 14 pages, 2 figures, accepted for publication in A

Design of Pulse Forming Networks Triggered by High-Power Hydrogen Thyratron

Hydrogen thyratron is a switching device invented based on the phenomenon of gas discharge, and it is widely used in the field of high-power pulse technology. The design of Pulse Forming Network (PFN) triggered by hydrogen thyratron aims to control the switch of subsequent circuit, and shorten the gate-cathode voltage and conduction delay time by increasing the rise rate of the trigger voltage. However, in the currently adopted series resonance network design schemes, usually the value of inductance is very large, which can easily lead to the decline in the electromagnetic compatibility performance; moreover, the large distribution of network component parameters will greatly increase the fabrication difficulties. In view of the features of high-power hydrogen thyratron and the design requirements of PFN, this paper adopted the series resonance network design scheme to devise network series and parameters of the PFN and analyze the shortcomings of the series resonance network design scheme; then, it used the anti-resonance network to design a three-stage transform algorithm model, so as to achieve the purpose of reducing the inductance of the PFN and the difficulty of capacitance model selection in engineering practice. At last, simulation results verified the correctness and feasibility of the designed three-stage transform algorithm model, providing evidences for the pulse network projects of hydrogen thyratron and other high-power equipment in terms of implementation paths, methods, and algorithm models

Decoy State Quantum Key Distribution With Modified Coherent State

To beat PNS attack, decoy state quantum key distribution (QKD) based on coherent state has been studied widely. We present a decoy state QKD protocol with modified coherent state (MCS). By destruction quantum interference, MCS with fewer multi-photon events can be get, which may improve key bit rate and security distance of QKD. Through numerical simulation, we show about 2-dB increment on security distance for BB84 protocol.Comment: 4 pages, 4 figure

Rigid vortices in MgB2

Magnetic relaxation of high-pressure synthesized MgB$_2$ bulks with different thickness is investigated. It is found that the superconducting dia-magnetic moment depends on time in a logarithmic way; the flux-creep activation energy decreases linearly with the current density (as expected by Kim-Anderson model); and the activation energy increases linearly with the thickness of sample when it is thinner than about 1 mm. These features suggest that the vortices in the MgB$_2$ are rather rigid, and the pinning and creep can be well described by Kim-Anderson model.Comment: Typo corrected & reference adde

(E)-(2,4-Dichloro­phen­yl)[2-hydr­oxy-6-(methoxy­imino)cyclo­hex-1-en­yl]methanone

The title compound, C14H13Cl2NO3, was obtained as the product of an attempted synthesis of herbicidally active compounds containing oxime ether and cyclo­hexenone groups. In the crystal structure, the mol­ecule adopts an endocyclic enol tautomeric form and the cyclo­hexene ring adopts a distorted envelope form. The oxime ether group has an E configuration, with the meth­oxy group anti to the ortho-chloro substitutent. Intra­molecular O—H⋯O and inter­molecular C—H⋯O hydrogen bonds are found in the crystal structure