Ultrashort Pulse Reflectometry for the Measurement of Electron Density Profiles

전자 밀도 분포 측정을 위한 극단 펄스 레플렉토메터리

  • 노영수 (숭실대 공대 전기공학과)
  • Published : 2004.01.01


An O-mode Ultrashort Pulse Reflectometry (USPR) system has been designed and developed for the measurement of electron density profiles on the Sustained Spheromak Physics Experiment (SSPX) spheromak. In the original design of SSPX, peak densities were envisioned to be in the range of 0.5-3${\times}$10$^{14}$ cm$^{-3}$ . The total duration of formation and sustained discharges is typically ∼2 msec. Moreover, diagnostic access on SSPX is severely restricted. Such high density and short duration plasmas coupled with stringent diagnostic access are quite challenging for conventional reflectometer systems. In USPR, the SSPX diagnostic requirements have been successfully satisfied by employing up-converting mixers and monostatic horn/waveguide configuration. As a result, the USPR system has proven its applicability for the density measurement of a future fusion device. In the density profile measurements, the USPR system is capable of routinely generating density profiles with a temporal resolution of 57 $\mu$s. This paper presents details regarding the USPR fundamental principles, associated subsystems and laboratory tests as well as the experimental results obtained on SSPX


Reflectometry;USPR;Plasma;SSPX;Density profile measurement


  1. D.M. Pozar, 'Microwave Engineering', Addison-Wesley Co. (1990)
  2. C. Laviron, et al., 'Reflectometry Techniques for Density Profile Measurements on Fusion Plasmas', Plasma Phys. Control. Fusion, 38 905 (1996) https://doi.org/10.1088/0741-3335/38/7/002
  3. H.S. McLean, et al., 'Plasma Diagnostics for the Sustained Spherornak Physics Experiment', Rev. Sci. Instrum., 72(1),556(2001) https://doi.org/10.1063/1.1318246
  4. V.L. Ginzburg, 'The Propagation of Electromagnetic Waves in Plasmas', Oxford, Pergamon (1970)
  5. E.T. Whitaker and G.N. Watson, 'Modem Analysis', Cambridge University Press (1962)
  6. C.W. Domier, et al., 'Development of Technology and Techniques for Reflectometry', Rev. Sci. Instrum. 63, 4666 (199) https://doi.org/10.1063/1.1143657
  7. R.H. Huddlestone and S.L. Leonard, 'Plasma Diagnostic Techniques', Academic Press, Inc. (1965)
  8. R.D. Hazeltine and J.D. Meiss, 'Plasma Confinement', Addison-Wesley Co. (1992)
  9. I.H. Hutchinson, 'Principles of Plasma Diagnostics', Cambridge University Press (1987)