- Volume 5 Issue 3
In this paper, the O-mode ultrashort-pulse reflectometry (USPR) millimeter-wave signals that propagate into the plasma and cover a frequency bandwidth of 33-158 GHz are examined numerically using MATLAB. Two important processes are involved in the computation: the propagation of the USPR impulse signal through a waveguide and the frequency up-conversion using millimeter-wave mixers. These mixers are limited to intermediate frequency signals that are less than 500 mV; thus, it is necessary to disperse the impulse signal into a chirped waveform using the waveguide. The stationary phase method is utilized to derive a closed-form formula for a chirped waveform under the assumption that the USPR impulse is Gaussian. In the process of frequency up-conversion, the chirped waveform is mixed with the mixer LO signal, and the lower frequency components of the RF signal are removed using high pass filters.
Chirped waveform;Frequency bandwidth;Frequency up-conversion;Method of stationary phase;Ultrashort-pulse reflectometry
- C. W. Domier, Y. Roh, and N. C. Luhmann, Jr., “Ultrashort Pulse Reflectometry for Electron Density Profile Measurements”, Rev. Sci. Instrum. Vol. 70, No. 1, pp. 1038-1040, Jan. 1999. https://doi.org/10.1063/1.1149530
- Y. Roh, C. W. Domier, and N. C. Luhmann, Jr., “Ultrashort Pulse Reflectometry for Electron Density Profile Measurements on SSPX”, Rev. Sci. Instrum. Vol. 72, No.1, pp. 332-334, Jan. 2001. https://doi.org/10.1063/1.1308999
- Y. Roh, C. W. Domier, and N. C. Luhmann, Jr., “Ultrashort Pulse Reflectometry for Density Profile and Fluctuation Measurements on SSPX”, Rev. Sci. Instrum. Vol. 74, No. 3, pp. 1518-1520, March 2003. https://doi.org/10.1063/1.1527254
- C. W. Domier, N. C. Luhmann, Jr., Y. Roh, H. S. McLean, E. B. Hooper, and D. N. Hill, “Ultrashort Pulse Reflectometer Performance on Sustained Spheromak Physics Experiment”, Rev. Sci. Instrum. Vol. 75, No. 10, pp. 3868-3670, Oct. 2004. https://doi.org/10.1063/1.1789604
- Y. Roh, “Ultrashort Pulse Reflectometry for the Measurement of Electron Density Profiles”, Trans. KIEE Vol.53C, No.1, pp. 8-14, Jan. 2004.
- H. S. McLean et al., “Plasma Diagnostics for the Sustained Spheromak Physics Experiment”, Rev. Sci. Instrum. Vol.72, No.1, pp. 556-558, Jan. 2001. https://doi.org/10.1063/1.1318246
- P. Stenius and B. York, “On the Propagation of Transients in Waveguides,” IEEE Antennas. Propag. Mag., Vol.37, No.2, pp. 39-44, April 1995. https://doi.org/10.1109/74.382337
- Reconstruction of the Electron Density Profile in O-mode Ultrashort Pulse Reflectometry using a Two-dimensional Finite Difference Time Domain vol.27, pp.7, 2013, https://doi.org/10.5207/JIEIE.2013.27.7.052
- Improvement of Power Spectrum in Ultrashort Pulse Reflectometry Signals Using Three Chirp Configuration vol.28, pp.3, 2014, https://doi.org/10.5207/JIEIE.2014.28.3.051