High speed conversion of infrared images with a planar gas discharge system

Portsel, L. М.; Astrov, Yu. A.; Reimann, Inge; Ammelt, E.; Purwins, H.‐G.

doi:10.1063/1.370297

Cited by 39 publications

(43 citation statements)

References 13 publications

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“…The scanning area is 1 µm×1 µm. The average height of surface irregularities is about 1.5 nm; the distributions of the heights relatively to the average value is plotted at the bottom of the figure for the untreated sample (curve 1), and samples exposed with ions (2) and with electrons (3). These data clearly demonstrate that there is no significant difference between these distributions (the width variation is less than 6Å).…”

Section: Afm Analysis Of the Semiconductor Electrode Surfacementioning

confidence: 82%

Modification of GaAs surface by low-current Townsend discharge

Gurevich¹,

Kittel²,

Hergenröder³

et al. 2010

J. Phys. D: Appl. Phys.

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Abstract. Influence of stationary spatially-homogeneous Townsend discharge on the (100) surface of semi-insulating GaAs samples is studied. Samples exposed to both electrons and ions in nitrogen discharge at the current density j=60 µA/cm 2 are studied by means of X-ray photoelectron spectroscopy, ellipsometry and atomic force microscopy. It is shown that exposure to low-energy ions (< 1 eV) changes crystal structure of the semiconductor on the depth up to 10-20 nm, although the stoichiometric composition does not change. The exposure to low-energy electrons (< 10 eV) forms an oxide layer, which is 5-10 nm thick. Atomic force microscopy demonstrates that the change in the surface potential of the samples may exceed 100 mV, for the both discharge polarities, while the surface roughness does not increase.

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Section: Afm Analysis Of the Semiconductor Electrode Surfacementioning

confidence: 82%

Modification of GaAs surface by low-current Townsend discharge

Gurevich¹,

Kittel²,

Hergenröder³

et al. 2010

J. Phys. D: Appl. Phys.

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“…The interest to dynamic solitary structures, in particular, in optical [4] and gas discharge systems [5] has been recently driven by their possible role in information transmission and processing.…”

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confidence: 99%

Nonlocal Boundary Dynamics of Traveling Spots in a Reaction-Diffusion System

Pismen

2001

Phys. Rev. Lett.

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The boundary integral method is extended to derive closed integro-differential equations applicable to computation of the shape and propagation speed of a steadily moving spot and to the analysis of dynamic instabilities in the sharp boundary limit. Expansion of the boundary integral near the locus of traveling instability in a standard reaction-diffusion model proves that the bifurcation is supercritical whenever the spot is stable to splitting, so that propagating spots can be stabilized without introducing additional long-range variables.Localized structures in non-equlibrium systems (dissipative solitons) have been studied both in experiments and computations in various applications, including chemical patterns in solutions [1] and on surfaces [2], gas discharges [3] and nonlinear optics [4]. The interest to dynamic solitary structures, in particular, in optical [4] and gas discharge systems [5] has been recently driven by their possible role in information transmission and processing.A variety of observed phenomena can be reproduced qualitatively with the help of simple reaction-diffusion models with separated scales [6][7][8][9][10]. Extended models of this type included nonlocal interactions due to gas transport [9,11], Marangoni flow [12] or optical feedback [4,13]. A great advantage of scale separation is a possibility to construct analytically strongly nonlinear structures in the sharp interface limit. An alternative approach based on Ginzburg-Landau models supplemented by quintic and/or fourth-order differential (Swift-Hohenberg) terms [14] have to rely on numerics in more than one dimension.Dynamical solitary structures are most interesting from the point of view of both theory and potential applications. Existence of traveling spots in sharp-interface models is indicated by translational instability of a stationary spot [11]. This instability is a manifestation of a general phenomenon of parity breaking (Ising-Bloch) bifurcation [15,16] which takes a single stable front into a pair of counter-propagating fronts forming the front and the back of a traveling pulse. Numerical simulations, however, failed to produce stable traveling spots in the basic activator-inhibitor model, and the tendency of moving spots to spread out laterally had to be suppressed either by global interaction in a finite region [11] or by adding an extra inhibitor with specially designed properties [17].The dynamical problem is difficult for theoretical study, since a moving spot loses its circular shape, and a free-boundary problem is formidable even for simplest kinetic models. Numerical simulation is also problematic, due to the need to use fine grid to catch sharp gradients of the activator; therefore actual computations were carried out for moderate scale ratios. A large amount of numerical data, such as the inhibitor field far from the spot contour, is superfluous. This could be overcome if it was possible to reduce the PDE solution to local dynamics of a sharp boundary. Unfortunately, a purely local equation of front motio...

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“…The efficiency of optimal control strategies is demonstrated by the fact that one can substantially decrease the duration of transient processes and nearly totally suppress an overshooting in the output signal. The results obtained can be used in applications of semiconductor gas discharge devices, such as fast converters of infrared images [15,18], and in the development of pulse sources of light, e.g., of ultraviolet excimer microdischarge lamps [13]. We indicate that the dynamical systems considered here and in [10][11][12] can be transformed into the same type of Lotka-Volterra system by an appropriate scaling of the state and time variables.…”

Section: Introductionmentioning

confidence: 68%

“…In the present article, we consider the problem of optimal control of one of the simplest gas discharge systems, which is the semiconductor gas discharge device initially designed for the conversion of infrared (IR) images to the visible range of light [15,18]. The feeding voltage is taken as the control function.…”

Section: Introductionmentioning

confidence: 99%