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  • 2000-2004  (8)
  • 1995-1999  (8)
  • 1990-1994  (16)
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  • 1
    Electronic Resource
    Electronic Resource
    Properties of diffraction gratings used as output couplers in a quasi-optical gyrotron (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2089-2102 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The design of a diffration grating used as an output coupler for a Fabry–Pérot resonator is presented. We then consider the problem of determining the distortion and the cross-polarization of the incident Gaussian beam. Different types of gratings and planes with straight or curvilinear grooves and elliptical, have been designed and built. The output pattern from a resonator using such a grating has been measured experimentally. We found that the elliptical grating generates the least distortion and cross-polarization. This result is attributed to the geometry of the grooves and is in excellent agreement with numerical calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353156
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Operation of a quasi-optical gyrotron with a Gaussian output coupler (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 3492-3500 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The operation of a 92 GHz quasi-optical gyrotron having a resonator formed by a spherical mirror and a diffraction grating placed in −1 order Littrow mount is presented. A power of 150 kW with a Gaussian output pattern was measured. The Gaussian content in the output was 98% with less than 1% of depolarization. By optimizing the magnetic field at fixed frequency, a maximum efficiency of 15% was reached.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871499
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    An improved Q-Machine source (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 1095-1100 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The development of a new Q-plasma source is described. Emphasis is given to the novel parts of the system which have been designed to produce long term, constant density plasmas with low fluctuation levels, as well as long machine operation time. Relevant plasma parameters are obtained by laser induced fluorescence which is used as a diagnostic on the barium plasma. Plasma densities are in the range of 108 cm−3 to 1011 cm−3, with an electron temperature of about 0.2 eV, and a perpendicular ion temperature of the same magnitude. The parallel ion temperature is one half the perpendicular value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141429
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    New vaporizing assembly for Q-plasma sources (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1407-1409 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design and operation of a new vaporizing assembly used for Q-plasma sources are described in this article. The vaporizing system, consisting of two ovens and an effuser, is used to vaporize and direct atoms onto a hot ionizer plate. The hot plate, which may be of tantalum, tungsten, or rhenium, singly ionizes the atoms on contact. The main advantages of this new assembly, compared to previous designs, are the production of higher plasma densities and the control of the radial plasma profile. The heaters of the two atomic beam ovens are independently controlled and monitored so that the gradients of the radial plasma profile can be modified. Plasma production with two ion species can also be performed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144052
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Direct visual observation of powder dynamics in rf plasma-assisted deposition (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1409-1411 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Contamination due to particles generated and suspended in silane rf plasmas is investigated. Powder is rendered visible by illumination of the reactor volume. This simple diagnostic for global, spatio-temporal powder dynamics is used to study particle formation, trapping, and powder reduction by power modulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105322
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The use of high-order TM0m0 modes of a resonant cavity for magnetized plasma density measurements (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 124-129 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of the application of high-order TM0m0 modes of a cylindrical cavity to the measurement of the density of a magnetized plasma column is presented. It is shown theoretically that judiciously chosen high-order modes have the potential advantages of both a wide operational range of densities, and a wide range for which a simple perturbation theory is valid. Furthermore, an experiment is described which shows that the TM060 mode can be excited with a sufficiently high Q value to allow accurate determination of the resonant frequencies, and hence plasma density. Favorable comparison between densities in the range 1010–1012 cm−3 measured by means of the resonant cavity technique and microwave interferometry is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345290
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Ion cyclotron wave excitation by double resonance coupling (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1171-1181 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A modulated high frequency wave is used to remotely excite low frequency oscillations in a linear, strongly magnetized plasma column. An electromagnetic wave is launched as an extraordinary mode across the plasma by an external waveguide in the upper-hybrid frequency regime f≈fUH≈fce≈8 GHz, with P≤2 W. By frequency modulating (at fFM≈1–60 kHz, with fci(approximately-equal-to)30 kHz) the pump wave, the resonant layer is swept radially across the profile and perpendicularly to the field lines at f=fFM. The resulting radial oscillation of the electron linear and nonlinear pressure can be considered to act as a source term for the ion wave. A localized virtual antenna is thereby created inside the plasma. Measurements of the ion dielectric response (interferograms and perturbed distribution functions) via laser-induced fluorescence identify the two branches (forward, or ion-acoustic-like, and backward, or Bernstein, modes) of the electrostatic dispersion relation in the ion cyclotron frequency range. By changing the modulation bandwidth, and thus the spatial excursion of the oscillating resonant layer, a control on the perpendicular wavelength of the excited mode can be exerted. In particular, the possibility of selective excitation of the ion Bernstein wave is demonstrated experimentally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859809
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Near threshold fatigue crack growth versus long finite life (2002)
    Oxford, UK : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 25 (2002), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A brief review of the discovery of the fatigue crack growth threshold is provided with a discussion of the main variables, Kmax and ΔK, which control the threshold over the low and high load ratio ranges, respectively. The significant effect on near threshold growth rates as illustrated by Donald are shown, for an example the aluminium alloy, 2324-T39. Attention is then turned to the ‘partial closure model’ as a means of correlating near threshold fatigue crack growth rates. This seems to be the most promising model with a physical basis. For this reason, the discussion goes on to present a new theoretical analysis of the load displacement record characteristics, which should accompany ‘partial closure’ of fatigue cracks. In addition it is concluded that secondary stress effects should be explored for near threshold fatigue crack growth rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-2695.2002.00560.x
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  • 9
    Electronic Resource
    Electronic Resource
    Secondary elastic crack tip stresses which may influence very slow fatigue crack growth (2002)
    Oxford, UK : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 25 (2002), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Secondary elastic crack tip stress intensity factors are defined in a convenient way consistent with the primary stress intensity factor definition. Methods of evaluation of these secondary stress intensity factors are developed. They are evaluated for example configurations with cracks. It is shown that the first secondary term may be sufficient to evaluate the effects of secondary stresses beyond the usual stress intensity factor and nominal normal stresses parallel to the crack direction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-2695.2002.00559.x
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    127Ce levels populated in the 4.2 s127Pr beta-decay (1995)
    Springer
    The European physical journal 351 (1995), S. 361-362 
    Details
    ISSN: 1434-601X
    Keywords: 23.20.Lv ; 27.60.+j
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract From new measurements, a half-live of 4.2±0.3 s has been clearly established in127Pr. This value confirms our first result [4] and rules out other data [5]. The127Pr activity was produced by bombarding92Mo or94Mo targets with 210 MeV40Ca beams. The mass identification has been made using an ion-guide coupled with an on-line isotope separator. The partial level scheme proposed for127Ce has been deduced from β-gated γ spectra and Xγ- and γγ-coincidences. A new band structure based on a 1/2+ state is established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01291139
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    Paper (German National Licenses)
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