ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Radio-frequency power combiner for cw and pulsed applications (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 449-452 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe the design and operation of a circuit to combine the output signals of two high-power radio transmitters into a single load. A working unit is realized using a commonly available ferrite and cheap coaxial cables. Performance tests indicate satisfactory operation from 3 to 50 MHz with less than 1 dB total power loss while guaranteeing adequate isolation between the transmitters. The power combiner can also be constructed specifically to withstand high line voltages for short time periods thus making it suitable for high-power pulsed applications such as plasma formation and heating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145155
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Plasmas as antennas: Theory, experiment and applications : The 41st annual meeting of the division of plasma physics of the american physical society (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 2198-2202 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In certain applications, the surface wave driven plasma column can replace metal as the guiding medium in radio frequency antennas. Such plasma antennas offer the possibility of low radar detectability and negligible mutual coupling when de-energized. Experimental results are presented confirming that the two most important physical issues, namely antenna efficiency and noise, are not compromised by the use of a plasma. It is also shown that the relatively high efficiency of the surface wave driven plasma column can be predicted by a simple calculation. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.874041
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Collisionless energy coupling to electrons by helicon waves in the near field of an antenna (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 529-536 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Linear kinetic damping mechanisms of helicon waves in helicon wave driven plasma sources are re-examined. It is demonstrated that a reversal of the phase velocity of the wave in the near field of an antenna can lead to a transient overshoot in the rate of work done by the wave. This overshoot occurs when the magnitude of the phase velocity is a few times the thermal speed and Landau damping is the dominant kinetic absorption mechanism. These conditions often occur in low field and low density sources. The overshoot in the rate of work done by the wave may be an order of magnitude larger than the far-field Landau absorption rate. The effect of collisions is also assessed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872152
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    An evaluation of different antenna designs for helicon wave excitation in a cylindrical plasma source (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 4396-4409 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A magnetohydrodynamic numerical model, based on the finite element method, is employed to analyze the antenna radiation resistance in a cylindrical helicon wave driven plasma source. The antenna radiation resistances of four commonly used antennas are compared. The effects on antenna radiation resistance of frequency, plasma density, density profile and the system dimensions are investigated. It is confirmed that m=+1 is the most strongly excited mode. It is shown that the plasma density gradient tends to suppress the excitation of negative m-modes. Some wave field patterns are also presented which demonstrate commonly observed features in the experiments such as the beat patterns of copropagating radial modes. The findings highlight the importance of antenna radiation resistance modelling as a first step to a self consistent model of the discharge physics of cool dense helicon wave driven sources. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872057
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Power coupling to helicon and Trivelpiece–Gould modes in helicon sources (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 564-571 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of finite electron mass on the helicon mode and the role of the Trivelpiece-Gould (TG) mode in helicon sources are considered. In an unbounded plasma these waves are commonly referred to as whistler waves. A simple cold plasma antenna-wave coupling code gives results which compare favorably with experimental observations of the whistler wave resonance cone. The connection between these cones and the Trivelpiece-Gould eigenmodes of bounded plasmas is discussed. The theory is applied to the study of antenna-wave coupling in helicon sources. It reveals that finite electron mass effects do not significantly improve antenna-wave coupling for ω/ωce〈0.5. It is also suggested that, because of the resonance cone dispersion, eigenmode cavity resonances of the Trivelpiece-Gould mode could be difficult to excite in practice. This precludes geometric resonances of the antenna impedance due to the existence of the TG mode as an explanation for the high plasma production efficiency of helicon sources. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872748
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Ion temperature and plasma flows in improved confinement mode in the H-1 heliac (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 3629-3634 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low and improved confinement modes in the H-1 heliac [M. G. Shats et al., Phys. Rev. Lett. 77, 4190 (1996)] are studied experimentally in rf-sustained (〈100 kW, 7 MHz) argon discharges at low magnetic fields (〈0.15 T). Surprisingly high ion temperature, measured using a retarding field energy analyzer, is found which increases across the transition to improved confinement mode from 40 to 80 eV, while the electron density increases by about 50%. Both toroidal and poloidal plasma flow velocities do not change across the transition. The increase in a radial electric field in high mode is balanced on average by a corresponding increase in the ion pressure gradient. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872258
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Helicon wave excitation and propagation in a toroidal heliac: Experiment and theory (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 803-810 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper a comparison between theoretical calculations and experimental measurements of helicon wave coupling by a partial-turn shielded antenna in a toroidal heliac is presented. Despite the complicated heliac geometry, the wave dispersion, field profiles, and antenna radiation resistance are described well by a cylindrical uniform plasma theory. It also presents a simple formula relating the radiation resistance to the measured wave magnetic field per unit antenna current. Finally, the scaling of these results to the Heliac-1 (H-1) [Fusion Technol. 17, 123 (1990)]; a larger heliac now operating at the Australian National University (ANU), is discussed. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871432
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Measurements and code comparison of wave dispersion and antenna radiation resistance for helicon waves in a high density cylindrical plasma source (1999)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 6 (1999), S. 703-712 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Helicon wave dispersion and radiation resistance measurements in a high density (ne(approximate)1019−1020 m−3) and magnetic field (B〈0.2 T) cylindrical plasma source are compared to the results of a recently developed numerical plasma wave code [I. V. Kamenski and G. G. Borg, Phys. Plasmas 3, 4396 (1996)]. Results are compared for plasmas formed by a double saddle coil antenna and a helical antenna. In both cases, measurements reveal a dominance of the m=+1 azimuthal mode to the exclusion of most other modes; in particular, no significant m=−1 mode was observed. The helical antenna, designed to launch m〈0 and m〉0 modes in opposite directions along the field, resulted in an axially asymmetric discharge with very little plasma on the m〈0 side of the antenna. For both antennas, good agreement of the antenna radiation resistance and wave dispersion with the model was obtained. It is concluded that unshielded antennas formed from current loops with an important |m|=1 component for the conditions of our experiment, couple most of their power to the m=+1 helicon mode and thus have negligible parasitic, nonhelicon plasma loading. This result greatly simplifies calculations of power balance in these sources by identifying the helicon as the mode by which energy is transferred to the plasma. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.873307
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Observation of the neoclassical current in the Small Heliac Experimental Apparatus (SHEILA) (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 3986-3991 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The first measurements of internal currents in a toroidal heliac are reported. It is suggested that the toroidal current observed in the Small Heliac Experimental Apparatus (SHEILA) [Nucl. Fusion 25, 1485 (1985)] in the low density regime consists mainly of the bootstrap current and the Pfirsch–Schlüter current, the net toroidal component corresponding to the uni-directional bootstrap current, and the asymmetric radial profile of the observed current indicating a mixture of bootstrap current with the bi-directional Pfirsch–Schlüter current. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872518
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The properties of the frequency splitting of the axisymmetric magnetoacoustic wave and an application to current profile diagnosis (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1191-1197 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the presence of finite plasma current, the axisymmetric (m=0) magnetoacoustic wave resonance exhibits a frequency splitting for finite toroidal mode number (n≠0) between oppositely directed traveling waves. Calculations are presented that demonstrate that Δ(1/f), the difference between the inverse resonance frequencies, is closely proportional to known moments of the plasma current profile and, in the limit where the radial wave number is much larger than the parallel wave number, is independent of the plasma mass density and its profile. A discussion of the observability of the splitting for the purpose of current profile diagnosis, given the theoretical and experimental data available, is also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859812
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...