Spectroscopy of a ferroelectric plasma cathode

Raitses

Journal of Applied Physics

2003

Self Cite

Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kG are presented. It is shown that the transverse magnetic field differently affects the operation of ferroelectric plasma cathodes in “bright” and “dark” emission modes in vacuum. In the bright mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the dark mode, the magnetic field impedes the electron emission. This result indicates the similarity of the dark emission mode to the surface preflashover, where the transverse magnetic field inhibits the development of secondary electron avalanches along the surface.

Section: Usamentioning

confidence: 99%

Ferroelectric cathodes in transverse magnetic fields

Raitses

Journal of Applied Physics

2003

Self Cite

“…Spectroscopic study of the FPS 5 showed that the plasma has a density of about 10 12 cm -3 and an electron temperature near 3 eV. However, spectroscopic measurements on sub-microsecond time scales are complicated and require collision-radiative codes for the modeling of non-steady-state plasmas.…”

Section: Introductionmentioning

confidence: 99%

“…4 Avalanching of field emission electrons along the ceramic surface causes the formation of plasma, which consists mostly of the materials of ferroelectric ceramics and the patterned electrode. 5 Diagnosing the FPS plasma is usually complicated by practical difficulties. The intrusion of small-scale probes in the near-surface region of the discharge perturbs substantially the distribution of the surface charge and consequently the operation of FPS.…”

Section: Introductionmentioning

confidence: 99%

“…However, spectroscopic measurements on sub-microsecond time scales are complicated and require collision-radiative codes for the modeling of non-steady-state plasmas. 5 In the majority of experiments, plasma measurements were performed in expanding plasma by probes placed distantly from the FPS surface. 6,7,8,9 Although placed distantly, the probes are exposed to strong broadband electromagnetic noise from the surface discharge.…”

Section: Introductionmentioning

confidence: 99%

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Measuring the plasma density of a ferroelectric plasma source in an expanding plasma

Journal of Applied Physics

2004

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The initial density and electron temperature at the surface of a ferroelectric plasma source were deduced from floating probe measurements in an expanding plasma. The method exploits negative charging of the floating probe capacitance by fast flows before the expanding plasma reaches the probe. The temporal profiles of the plasma density can be obtained from the voltage traces of the discharge of the charged probe capacitance by the ion current from the expanding plasma. The temporal profiles of the plasma density, at two different distances from the surface of the ferroelectric plasma source, could be further fitted by using the density profiles for the expanding plasma. This gives the initial values of the plasma density and electron temperature at the surface. The method could be useful for any pulsed discharge, which is accompanied by considerable electromagnetic noise, if the initial plasma parameters might be deduced from measurements in expanding plasma.

“…In the plasma of surface discharges, probe measurements of plasma parameters are possible only at a distance, in the expanding plasma. 1 Recent spectroscopic studies 6,7 did not allow retrieving unambiguous values of both initial values of the plasma density and the electron temperature in the channel, or stem, of the discharge. Recently, a method of deducing of the initial plasma parameters from temporal profiles of the density of expanding plasma has been developed.…”

Section: Introductionmentioning

confidence: 99%

Operation of ferroelectric plasma sources in a gas discharge mode

2004

Physics of Plasmas

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Ferroelectric plasma sources in vacuum are known as sources of ablative plasma, formed due to surface discharge. In this paper, observations of a gas discharge mode of operation of the ferroelectric plasma sources (FPS) are reported. The gas discharge appears at pressures between ∼20 and ∼80 Torr. At pressures of 1–20 Torr, there is a transition from vacuum surface discharge to the gas discharge, when both modes coexist and the surface discharges sustain the gas discharge. At pressures between 20 and 80 Torr, the surface discharges are suppressed, and FPS operates in pure gas discharge mode, with the formation of almost uniform plasma along the entire surface of the ceramics between strips. The density of the expanding plasma is estimated to be about 1013 cm−3 at a distance of 5.5 mm from the surface. The power consumption of the discharge is comparatively low, making it useful for various applications. This paper also presents direct measurements of the yield of secondary electron emission from ferroelectric ceramics, which, at low energies of primary electrons, is high and dependent on the polarization of the ferroelectric material.