共查询到20条相似文献,搜索用时 15 毫秒
1.
Quasi-simultaneous laser action in the UV (0.337 μm) and the IR (10.6 μm) was observed from a pulsed laser with a sliding discharge plasma cathode. The laser operates at atmospheric pressure, with a gas mixture of CO2/N2/He, at a 0.26/0.50/4.0 lmin−1 flow rate. Output energies of 30 mJ in the IR and 0.35 mJ in the UV were obtained, from a laser discharge volume of 38.0×1.0×2.8 cm3. The optimum gas mixtures have been determined and the temporal behavior of the discharge parameters, the performance characteristics of the laser and the beam spatial distributions were investigated. 相似文献
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Chang X Wu Q Ben-Zvi I Burrill A Kewisch J Rao T Smedley J Wang E Muller EM Busby R Dimitrov D 《Physical review letters》2010,105(16):164801
The diamond amplifier (DA) is a new device for generating high-current, high-brightness electron beams. Our transmission-mode tests show that, with single-crystal, high-purity diamonds, the peak current density is greater than 400 mA/mm2, while its average density can be more than 100 mA/mm2. The gain of the primary electrons easily exceeds 200, and is independent of their density within the practical range of DA applications. We observed the electron emission. The maximum emission gain measured was 40, and the bunch charge was 50 pC/0.5 mm2. There was a 35% probability of the emission of an electron from the hydrogenated surface in our tests. We identified a mechanism of slow charging of the diamond due to thermal ionization of surface states that cancels the applied field within it. We also demonstrated that a hydrogenated diamond is extremely robust. 相似文献
4.
Ya.E. Krasik A. Dunaevsky J. Felsteiner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(3):345-348
We studied the emission properties of carbon fiber cathodes. These cathodes were made either of a single carbon fiber or of
carbon fabric, or of an array of carbon fiber bundles. It was found that an intense emission of electrons occurs from a plasma
which is formed on the carbon fiber surface as a result of a flashover process. In addition, the time delay in the appearance
of the electron emission with respect to the start of the accelerating voltage pulse was found to depend strongly on the voltage
growth rate. A simple model of the plasma formation is suggested.
Received 12 March 2001 相似文献
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T. Altherr 《Zeitschrift fur Physik C Particles and Fields》1990,47(4):559-563
We give the technics for the calculation of production and energy loss rates for axion-like particles (scalar or pseudo-scalar coupling to the gauge boson) from a hot QED (or QCD) heat bath. We compute the contribution coming from, the decay mode of a transverse to a longitudinal photon (or gluon). The energy loss rate for this process behaves asT 7. Considering the supernova SN1987A event, this behaviour could improve the upper bound on the coupling constant between asions and photons. 相似文献
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A. G. Zagorodnii A. S. Usenko I. P. Yakimenko 《Radiophysics and Quantum Electronics》1994,37(10):798-814
The electromagnetic radiation field of sources arbitrarily distributed throughout space is found for the case of a semi-bounded plasma when the charged plasma particles are specularly and randomly scattered by the plasma interface. The spectral distributions of the thermal radiation emitted by a nonisothermal semi-bounded plasma into an external medium having a nonzero temperature are calculated.Institute of Theoretical Physics, Ukrainian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, No. 10, pp. 1237–1261, October, 1994. 相似文献
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The interaction of the plasma formed at emission centers of an electron source using explosive electron emission with the cathode surface is studied. It is found that the plasma flux does not flow around obstacles located in its path and is effectively deionized upon incidence on the wall.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 26–29, November, 1981. 相似文献
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The effect of fast charged and neutral particles on the emission properties of different materials is investigated. In many
plasma devices, a flux of fast atoms and ions produces a specific self-sustained state of the layer near the cathode surface.
In particular, this layer is saturated by working gas atoms to a depth of several monolayers. This state variously modifies
different types of emission. Potential emission, taking place under the action of metastable atoms and ions, weakens because
of a rise in the work function. On the contrary, kinetic emission, which is due to fast heavy particles, is enhanced, since
energy losses in the modified near-surface layer increase. Photoemission resulting under the action of resonance radiation
increases considerably, and its mechanism changes. 相似文献
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A. P. Semenov 《Technical Physics》2007,52(2):276-280
A new geometrical relationship between the shape and dimensions of the cathode cavity of a reflex discharge with a cold hollow cathode is determined. The discharge characteristics and the emission properties of the discharge plasma are investigated experimentally. The conditions are determined for generating a cathode plasma that is highly inhomogeneous in the radial direction and the possibility of creating such a plasma is demonstrated. The existence of a stationary double electric layer with a potential drop of 14–16 V in the aperture of the cathode cavity is revealed. Specific features of the longitudinal extraction of plasma ions through the wall layer of the reflex and hollow cathodes are considered. 相似文献
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A neutron yield of } 5×105
D-D neutrons/discharge was obtained when 0.1 KJ of energy was pumped into a plasma focus of Mather type. The neutron yield was
measured by a high sensitivity silver activation counter. The results are compared with those of other laboratories and it
is found that neutron yield scales asE
1.73 orI
4.29 in the 0.1–500 KJ region. 相似文献
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V. K. Malyutenko A. I. Liptuga V. A. Botte V. I. Chernyakhovskii 《Journal of Applied Spectroscopy》1991,55(4):1024-1028
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 4, pp. 624–629, October, 1991. 相似文献
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G. Tomassetti A. Ritucci L. Palladino L. Reale O. Consorte S. V. Kukhlevsky I. Zs. Kozma F. Flora L. Mezi J. Kaiser O. Samek M. Liška 《Czechoslovak Journal of Physics》2002,52(3):405-416
We present the characterization of an apparatus generating XUV radiation by a high peak value (20–40) kA and short rise time
(≈ 20 ns) current pulse in a capillary discharge channel (up to 20 cm in length) filled by argon gas. The apparatus has been
developed with the purpose of production of an intensive spontaneous emission in the spectral region of (2–50) nm and study
of the z-pinch conditions for obtaining the laser generation in the Nelike Ar at 46.9 nm. The current pulses are generated
by the direct discharge of a 7 nF water dielectric capacitor resonantly charged up to 400 kV by a six-stages Marx generator.
The XUV radiation emitted during the radial compression of the plasma column is measured using calibrated PIN diodes, filters
and multilayer mirrors in order to test the z-pinch plasma collapse and to measure the conversion efficiency of the electrical
energy into the XUV radiation.
This work is supported by the Italian National Institute of Nuclear Physics and in part by the Italian National Institute
of Matter Physics. 相似文献
16.
Selective plasma etching and hydrogen plasma treatment were introduced in turn to improve field emission characteristics of screen-printed carbon nanotubes (CNTs) cold cathode, which was prepared by using slurry of mixture of multi-wall CNTs, organic vehicles and inorganic binder, i.e. silicon dioxide sol. The results show that selective plasma etching process could effectively remove parts of surface inorganic vehicle (SiO2) layer and expose more smooth and clean CNTs on cathode surface, which could significantly decrease the operating field of CNTs cathode. There are some nanoparticles emerging on the out of CNTs wall after hydrogen plasma treatment, which are equivalent to increase field emission point of cathode. At the same time, these nanoparticles can increase the local electric field of CNTs, which can decrease operating voltage of CNTs cathode and improve uniformity field emission. 相似文献
17.
R. Jones 《Physics letters. A》1977,62(7):493-494
The usual limitations on extracted ion current and energy partition with electrons can be relaxed for an ion source operated with a non-stationary sheath. 相似文献
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Tejero EM Amatucci WE Ganguli G Cothran CD Crabtree C Thomas E 《Physical review letters》2011,106(18):185001
Laboratory observations of electromagnetic ion-cyclotron waves generated by a localized transverse dc electric field are reported. Experiments indicate that these waves result from a strong E×B flow inhomogeneity in a mildly collisional plasma with subcritical magnetic field-aligned current. The wave amplitude scales with the magnitude of the applied radial dc electric field. The electromagnetic signatures become stronger with increasing plasma β, and the radial extent of the power is larger than that of the electrostatic counterpart. Near-Earth space weather implications of the results are discussed. 相似文献
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The total and specular light emitted at 2ω by a laser produced plasma (τ = 30 ps, λ = 1 μm) have been measured versus intensity (1012-1014 W/cm2), polarization and angle of incidence of the laser beam. The possibility for second harmonic to arise from resonant absorption, through a rippled critical surface, or from parametric decay instability is discussed. 相似文献