The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
M S Shur - One of the best experts on this subject based on the ideXlab platform.
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mechanism of self excitation of terahertz Plasma Oscillations in periodically double gated electron channels
Journal of Physics: Condensed Matter, 2008Co-Authors: Victor Ryzhii, Akira Satou, M Ryzhii, Taiichi Otsuji, M S ShurAbstract:We develop a device model for a heterostructure device with an electron channel and with a periodic system of interdigitated gates. Using this model, we find the conditions of the self-excitation of Plasma Oscillations in portions of the channel. It is shown that the self-excitation of Plasma Oscillations in these devices and the terahertz emission observed in the experiments (Otsuji et al 2006 Appl. Phys. Lett. 89 263502; Meziani et al 2007 Appl. Phys. Lett. 90 061105; Otsuji et al 2007 Solid-State Electron. 51 1319) might be attributed to the electron-transit-time effect in the barrier regions.
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resonant terahertz detector utilizing Plasma Oscillations in two dimensional electron system with lateral schottky junction
Japanese Journal of Applied Physics, 2006Co-Authors: V Ryzhii, M S ShurAbstract:We propose a novel resonant detector of terahertz radiation based on a heterostructure with an ungated two-dimensional electron channel, with a lateral Schottky junction at one of the channel edges, substantiate its operation, and evaluate the device characteristics. We demonstrate that the detector responsivity can exhibit sharp resonant maxima at the frequencies pertaining to the Plasma Oscillations. As shown, the peak values of the responsivity of the detector proposed can exceed the responsivity of the standard Schottky detectors by several orders of magnitude if the electron mobility in the channel is sufficiently high.
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resonant excitation of Plasma Oscillations in a partially gated two dimensional electron layer
Journal of Applied Physics, 2005Co-Authors: V V Popov, O V Polischuk, M S ShurAbstract:We have solved the problem of diffraction of terahertz radiation on a perfectly conductive gate strip that partially screens a two-dimensional (2D) electron layer located at some distance from the gate. Scattering and absorption spectra of such a structure reveal the fundamental Plasma resonance excited under the gate. We have shown that the absorption enhancement factor at Plasma resonance may reach very high values (up to 60). However, for narrow gate strips (with the width less than 100nm) the resonant scattering length of such a scatterer is shorter than its resonant absorption length by four orders of magnitude, which means that the gated plasmons in this case weakly couple to the terahertz radiation. We discuss the effects of interaction between Plasma Oscillations in gated and ungated regions of 2D electron layer and provide a qualitative explanation of the rather intensive terahertz emission from unstable gated plasmons in a 60-nm gate field-effect transistor observed recently.
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Plasma mechanism of terahertz photomixing in high electron mobility transistor under interband photoexcitation
Journal of Applied Physics, 2002Co-Authors: V Ryzhii, A. Satou, I Khmyrova, P O Vaccaro, Tahito Aida, M S ShurAbstract:We show that modulated near-infrared radiation can generate terahertz Plasma Oscillations in the channel of a high-electron mobility transistor. This effect is associated with a temporarily periodic injection of the electrons photoexcited by modulated near-infrared radiation into the transistor channel. The excitation of the Plasma Oscillations has the resonant character. It results in the pertinent excitation of the electric current in the external circuit that can be used for generation of terahertz electromagnetic radiation.
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analysis of tunneling injection transit time effects and self excitation of terahertz Plasma Oscillations in high electron mobility transistors
Japanese Journal of Applied Physics, 2002Co-Authors: V Ryzhii, M S ShurAbstract:We analyze dynamic behavior of the electron system in high-electron mobility transistors (HEMTs) associated with tunneling injection from the two-dimensional channel into the gate under forward bias. We show that the propagation of the injected electrons across the gate layer can result in the self-excitation of Plasma Oscillations in the HEMT when the transit-time and Plasma resonances are close. The resonant frequencies in HEMTs with reasonable parameters correspond to the terahertz range. The criterion of the Plasma instability is expressed via the structural parameters. The self-excitation of the Plasma Oscillations can be used to generate terahertz radiation.
F Skiff - One of the best experts on this subject based on the ideXlab platform.
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complete spectrum of kinetic eigenmodes for Plasma Oscillations in a weakly collisional Plasma
Physical Review Letters, 2004Co-Authors: A Bhattacharjee, F SkiffAbstract:Kinetic eigenmodes of Plasma Oscillations in a weakly collisional Plasma, described by a collision operator of the Fokker-Planck type, are obtained in closed form for initial-value as well as for boundary-value problems. These eigenmodes, which are smooth and compose a complete discrete spectrum, play the same role for weakly collisional Plasmas as the Case-Van Kampen modes do for collisionless Plasmas.
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kinetic eigenmodes and discrete spectrum of Plasma Oscillations in a weakly collisional Plasma
Physical Review Letters, 1999Co-Authors: A Bhattacharjee, F SkiffAbstract:The damping of Plasma Oscillations in a weakly collisional Plasma is revisited using a Fokker-Planck collision operator. It is shown that the Case--Van Kampen continuous spectrum is eliminated in the limit of zero collision frequency and replaced by a discrete spectrum. The Landau-damped solutions are recovered in this limit, but as true eigenmodes of the weakly collisional system. For small but nonzero collision frequency, the spectra and eigenmodes are qualitatively different from their counterparts in the collisionless theory. These results are consistent with recent experimental findings.
R Koch - One of the best experts on this subject based on the ideXlab platform.
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radio frequency surface Plasma Oscillations electrical excitation and detection by ar ag 111
Scientific Reports, 2017Co-Authors: Giulia Serrano, Stefano Tebi, Stefan Wiespointnerbaumgarthuber, Stefan Mullegger, R KochAbstract:We electrically excite surface Plasma Oscillations on a Ag(111) single crystal by alternating electric charging at radio frequency. The radio frequency signal energy of 2.2 μeV, used to induce surface Plasma Oscillations, is about 5 to 6 orders of magnitude lower than the plasmon energies reachable by optical excitation or electron impact. The detection of the surface Plasma Oscillations is achieved by nano-fabricated 2D single-crystal sensor-islands of Ar atoms, which are shown by imaging with a scanning tunneling microscope to restructure in response to the radio frequency surface Plasma Oscillations, providing nanometer spatial resolution and a characteristic decay time of ≈150 ns.
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Radio frequency surface Plasma Oscillations: electrical excitation and detection by Ar/Ag(111)
Scientific Reports, 2017Co-Authors: Giulia Serrano, Stefano Tebi, Stefan Mullegger, Stefan Wiespointner-baumgarthuber, R KochAbstract:We electrically excite surface Plasma Oscillations on a Ag(111) single crystal by alternating electric charging at radio frequency. The radio frequency signal energy of 2.2 μ eV, used to induce surface Plasma Oscillations, is about 5 to 6 orders of magnitude lower than the plasmon energies reachable by optical excitation or electron impact. The detection of the surface Plasma Oscillations is achieved by nano-fabricated 2D single-crystal sensor-islands of Ar atoms, which are shown by imaging with a scanning tunneling microscope to restructure in response to the radio frequency surface Plasma Oscillations, providing nanometer spatial resolution and a characteristic decay time of ≈150 ns.
William S. Kurth - One of the best experts on this subject based on the ideXlab platform.
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Electron Plasma Oscillations Upstream of the Solar Wind Termination Shock
2016Co-Authors: Donald A. Gurnett, William S. Kurth, Hz WhereAbstract:Electron Plasma Oscillations have been detected upstream of the solar wind ter-mination shock by the Plasma wave instrument on the Voyager 1 spacecraft. These waves were first observed on 11 February 2004, at a heliocentric radial distance of 91.0 astronomical units, and continued sporadically with a gradually increasing occurrence rate for nearly a year. The last event occurred on 15 December 2004, at 94.1 astronomical units, just before the spacecraft crossed the termination shock. Since then, no further electron Plasma Oscillations have been observed, consistent with the spacecraft having crossed the termination shock into the heliosheath. Electron Plasma Oscillations, also known as Langmuir waves, are one of the oldest known and most widely studied of all Plasma wave phenomena (1). For many years it has been known that electron Plasma Oscillations are generated ahead of planetary bow shocks by energetic electrons escaping into the solar wind upstream of the shock (2–7). This close relationship led Kurth and Gurnett (8) to pre-dict that electron Plasma Oscillations would be present upstream of the solar wind termination shock. Here, we report the initial observations of these waves. Electron Plasma Oscillations are electro-static Oscillations that occur at a characteristic frequency of the Plasma known as the electron Plasma frequency. The electron Plasma fre-quency is given by fp 0 8980 ffiffiffiffi n
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Evidence for a Shock in Interstellar Plasma: Voyager 1
The Astrophysical Journal, 2013Co-Authors: Leonard F. Burlaga, Donald A. Gurnett, N. F. Ness, William S. KurthAbstract:Voyager 1 (V1) observed electron Plasma Oscillations preceding a jump by a factor of 1.4 in the magnetic field intensity B near the end of 2012. The frequency of the electron Plasma Oscillations gives an electron density ne = 0.05 cm–3, which implies that V1 was immersed in Plasma from the interstellar medium. The last day on which Plasma Oscillations were observed is day 332, 2012, and the jump in the B was centered on day 335, 2012 after a data gap in the wave data. The close association between the electron Plasma Oscillations and the jump in B suggests a causal connection, such as that frequently observed between electron Plasma Oscillations and interplanetary shocks at 1 AU. Based on the observed parameters and the smooth profile of B(t), the jump in B appears to be associated with a weak, subcritical, laminar, low beta, quasi-perpendicular, resistive, collisionless shock. However, the width of the jump is of the order of 104 times that expected for such a stationary shock at 1 AU. The large width of the jump in B might be the result of differences between the structure of shocks in the interstellar medium and the Plasma near 1 AU. Alternatively, the subcritical resistive shock might have decayed during a few days after producing the Plasma waves, leaving a broad profile in B(t) without significantly changing ambient parameters. Another possibility is that the jump in B is a pressure wave.
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Electron Plasma Oscillations upstream of the solar wind termination shock.
Science, 2005Co-Authors: Donald A. Gurnett, William S. KurthAbstract:Electron Plasma Oscillations have been detected upstream of the solar wind termination shock by the Plasma wave instrument on the Voyager 1 spacecraft. These waves were first observed on 11 February 2004, at a heliocentric radial distance of 91.0 astronomical units, and continued sporadically with a gradually increasing occurrence rate for nearly a year. The last event occurred on 15 December 2004, at 94.1 astronomical units, just before the spacecraft crossed the termination shock. Since then, no further electron Plasma Oscillations have been observed, consistent with the spacecraft having crossed the termination shock into the heliosheath.
T E Cowan - One of the best experts on this subject based on the ideXlab platform.
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two surface plasmon decay of Plasma Oscillations
Physics of Plasmas, 2015Co-Authors: T Kluge, J Metzkes, K Zeil, M Bussmann, U Schramm, T E CowanAbstract:The interaction of ultra-intense lasers with solid foils can be used to accelerate ions to high energies well exceeding 60 MeV [Gaillard et al., Phys. Plasmas 18, 056710 (2011)]. The non-linear relativistic motion of electrons in the intense laser radiation leads to their acceleration and later to the acceleration of ions. Ions can be accelerated from the front surface, the foil interior region, and the foil rear surface (target normal sheath acceleration (TNSA), most widely used), or the foil may be accelerated as a whole if sufficiently thin (radiation pressure acceleration). Here, we focus on the most widely used mechanism for laser ion-acceleration of TNSA. Starting from perfectly flat foils, we show by simulations how electron filamentation at or inside the solid leads to spatial modulations in the ions. The exact dynamics depend very sensitively on the chosen initial parameters which has a tremendous effect on electron dynamics. In the case of step-like density gradients, we find evidence that suggests a two-surface-plasmon decay of Plasma Oscillations triggering a Raileigh-Taylor-like instability.
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two surface plasmon decay of Plasma Oscillations
arXiv: Plasma Physics, 2015Co-Authors: T Kluge, J Metzkes, K Zeil, M Bussmann, U Schramm, T E CowanAbstract:The interaction of ultra-intense lasers with solid foils can be used to accelerate ions to high energies well exceeding 60 MeV. The non-linear relativistic motion of electrons in the intense laser radiation leads to their acceleration and later to the acceleration of ions. Ions can be accelerated from the front surface, the foil interior region, and the foil rear surface (TNSA, most widely used), or the foil may be accelerated as a whole if sufficiently thin (RPA). Here, we focus on the most widely used mechanism for laser ion-acceleration of TNSA. Starting from perfectly flat foils we show by simulations how electron filamentation at or inside the solid leads to a spatial modulations in the ions. The exact dynamics depend very sensitively on the chosen initial parameters which has a tremendous effect on electron dynamics. In the case of step-like density gradients we find evidence that suggests a two-surface-plasmon decay of Plasma Oscillations triggering a Raileigh-Taylor-like instability.