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  • 1
    Electronic Resource
    Electronic Resource
    A large-area plasma source excited by a tunable surface wave cavity (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2331-2337 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A large-area high-density microwave plasma is successfully generated at low pressure by a tunable surface wave cavity which consists of a 12 period vane-type slow wave structure. This cavity is operated in the π mode and resonant at 2.45 GHz. The plasma area is in excess of 50 cm×25 cm with a uniformity of ±10% at pressures less than 30 mTorr. A plasma surface wave has been excited so that a plasma density as high as 1.0×1012 cm−3 can be achieved at 30 mTorr for a microwave power of 2.0 kW. The plasma temperature is ∼1.5 eV and the plasma potential is ∼12 V. Above all, the number of the periods of the π-mode cavity can be increased without changing the resonance frequency and the distribution of the microwave fields such that this plasma source is easy to up-scaled. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149759
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  • 2
    Electronic Resource
    Electronic Resource
    Backward traveling wave amplification in the gyrotron (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 4140-4143 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The gyrotron backward traveling wave amplifier (gyro-BTWA) is introduced and characterized by a linear theory in this study. The gain mechanism, instead of a convective instability, is due to the interference among three backward waves. As a result, a high gain, tunable amplifier can be realized with a short interaction length for lower beam voltage and current. The theoretical results show that a gain of 25 dB at 39.47 GHz can be achieved with an interaction length of 4 cm for a 10-kV, 0.554-A electron beam. These features could make this device as a promising coherent radiation source in the microwave and millimeter wave regimes. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872534
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  • 3
    Electronic Resource
    Electronic Resource
    Linear theory of gyrotron traveling wave tubes with nonuniform and lossy interaction structures (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 2454-2462 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A linear theory model is developed to analyze gyrotron traveling wave tubes (gyro-TWT) employing nonuniform interaction structures, which can be tapered wall waveguide, severed tubes, or distributed lossy wall waveguides. Effects of the wall loss, reflections caused by the nonuniformity of the waveguide, and beam–wave interactions inside the sever region are incorporated in this theory. In addition, self-excited oscillations in the gyro-TWT induced by absolute instabilities or reflections can also be studied by the same theory. Good agreements with the self-consistent particle-tracing code have been achieved. This theory can be used to provide a first-cut design of a stable gyro-TWT. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872922
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  • 4
    Electronic Resource
    Electronic Resource
    On the launching loss and the Weibel instability of the gyrotron traveling wave tube (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 578-585 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A linear theory and a self-consistent theory are used to study the launching loss and the Weibel instability of the gyrotron traveling wave tube (gyro-TWT). Numerical results and a simplified analytical model both show that the launching loss is inversely proportional to the growth rate of the wave, and proportional to the difference between the propagation constant of the forward constant amplitude wave and that of the forward growing wave. In addition, the prediction of the Weibel instability in a fast wave interaction structure by the dispersion relation is verified to be valid even though the assumption of close resonance condition of the linear theory breaks down in this region. Nevertheless, this instability is overwhelmed by the launching loss. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870983
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  • 5
    Electronic Resource
    Electronic Resource
    Starting oscillation conditions for gyrotron backward wave oscillators (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3093-3099 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A generalized linear theory that allows for mismatched boundary conditions was used in determining the starting oscillation conditions for gyrotron backward wave oscillators (gyro-BWO). The results reveal that the gyro-BWO interaction is normally caused by the interference between a constant-amplitude backward wave and a decaying backward wave. The latter becomes a forward-growing wave if the operating frequency is close to the waveguide cutoff frequency. The starting oscillation length for a reflection-type gyro-BWO is shorter than that of a matched-type gyro-BWO. The mismatch has more of an effect upon the onset of a gyro-BWO, which is operated close to the cutoff frequency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870500
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  • 6
    Electronic Resource
    Electronic Resource
    Experimental study of the plasma resonance in a planar surface wave plasma (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 3195-3198 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this study, the plasma resonance in a surface wave sustained plasma was investigated. Surface wave discharges have been successfully generated by a microwave planar vane-type slow wave structure. Experimental results clearly demonstrated that the amplitude of the electric field of the microwave always became a local maximum in the position where the plasma density was equal to the same value. When the operating gas pressure and the input microwave power were varied to change the plasma density profile, the location of the maximum of the electric field was found to shift in compliance with the plasma density profile. Meanwhile, the peak of the resonance response was found to be proportional to the plasma density gradient while the spatial width of plasma resonance was inversely proportional to the plasma density gradient. These results were qualitatively in accordance with the theory. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1379342
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  • 7
    Electronic Resource
    Electronic Resource
    Spectral domain analysis of open cavities (1992)
    Springer
    International journal of infrared and millimeter waves 13 (1992), S. 1571-1598 
    Details
    ISSN: 1572-9559
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01009236
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  • 8
    Electronic Resource
    Electronic Resource
    Experimental Study of a High Power Coupler for a Tunable Cavity Formed by a Vane-Type Structure (1999)
    Springer
    International journal of infrared and millimeter waves 20 (1999), S. 1155-1168 
    Details
    ISSN: 1572-9559
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this study, a high power coupler designed for a tunable planar cavity is experimentally tested. The cavity consists of a periodical vane-type structure, of which the height of the vane can be mechanically adjusted so that the resonance frequency can be fine tuned. The cavity is designed to be operated at π mode and resonant at 2.45 GHz. The high power coupler is composed of a rectangular waveguide and a cylindrical ceramic rod with tapered ends. One end of the ceramic rod is intruded into the gap between two vanes of the cavity. Through this coupler, the TE10 mode of the rectangular waveguide is converted into the TE11 mode of the ceramic rod and then couples to the TEM mode in the gap between vanes of the cavity. Experimental results show that a microwave power up to 5 kW can be effectively transmitted to excite the π mode of the cavity . This cavity can be used to excite large area plasmas
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021732824839
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  • 9
    Electronic Resource
    Electronic Resource
    Experimental Study of a Slot Antenna Excited by a TE011 Mode Coaxial Cavity (1999)
    Springer
    International journal of infrared and millimeter waves 20 (1999), S. 897-911 
    Details
    ISSN: 1572-9559
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A slot antenna is developed to excite the high harmonic waveguide mode for generating large-area plasmas. This antenna consists of a TE011 mode coaxial cavity with the axial slots positioned on equal interval on the inner wall. The waves radiated from those slots can excite the high harmonic mode in the central area. With the azimuthal symmetric wave field of the TE011 mode, the number of the slots can be chosen to match the field pattern of the high harmonic mode. In this report, the dispersion relation of the coaxial waveguide, the coupling scheme and the mode competition of the cavity are studied. A method has been successfully developed to suppress the TE121 mode which is the most competing mode to the TE011 mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021726302008
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  • 10
    Electronic Resource
    Electronic Resource
    Linear Analysis of Traveling Wave Tubes with Nonuniform Lossy Interaction Structures (1999)
    Springer
    International journal of infrared and millimeter waves 20 (1999), S. 1353-1362 
    Details
    ISSN: 1572-9559
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A linear theory model is developed to analyze traveling wave tubes (TWT) employing distributed wall loss. The loss can be a function of position. The electronic and circuit equation are derived, taking into account the spatial variation of the circuit loss. This model can be used to provide a first-cut design of the TWT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021774828107
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