Surface discharge plasma induced by spontaneous polarization switching

Abstract

A flashover plasma has been induced by spontaneous polarization switching on a polar surface of the ferroelectric crystal triglycine sulphate (TGS). The effect has not been observed in the paraelectric phase. The threshold switching voltage for a surface flashover ignition was as low as 100 V for pulsed and ac voltage. A mechanism of plasma initiation on a ferroelectric surface is proposed. It is assumed that the plasma is ignited by electron emission initiated by polarization switching. Subsequent electron avalanching occurs as a result of the high potential gradient along the ferroelectric surface caused by inhomogeneous polarization switching. Electrons and ions with energies up to several hundreds of eV were been recorded due to a high surface potential of the switched ferroelectric.

Energy distribution of plasma-assisted electron and ion emission from TGS single crystals

“…It was reported earlier in [5,17] that under the influence of a drive ac electric field the TGS crystal samples can operate as a source of electrons with energies up to a few tens of eV and even the electron energies can be gained to about 200 eV [22]; under plasma-assisted surface processes the electrons and ions with energies up to a few hundred of eV can be produced on pure and La alanine doped TGS single crystals [17][18][19][20][21].…”

“…If ion emission assists electron emission (for positive charging of the emitting surface by switching process or mere charging of the sample), the energy of electrons was focused at about 200 eV; the ions have energies up to about 400 eV. The electrons and ions with energies up to 300 eV extracted from surface plasma initiated on TGS sample surface during switching process were reported by Rosenman et al [20] and Shur et al [21]. The electrons with energies extend up to a few hundreds of eV, produced on TGS single crystals by ac (300 Hz) switching sinusoidal voltage, were also measured by Klias et al [22].…”

Ion emission from ferroelectrics

“…Such ion emission ͓for short ferroelectric ion emission ͑FEIE͔͒ has been theoretically predicted 4 and massunresolved positive ion currents observed experimentally. 5 No negative ion emission has been reported so far.…”

X-ray fluoresced high-Z (up to Z=82) K x rays produced by LiNbO3 and LiTaO3 pyroelectric crystal electron accelerators

“…Reference 4, a recent comprehensive review article, is representative but does not suggest that pyroelectric crystals can produce focused, stable energetic electron beams capable of ionizing K electrons in high-Z materials and producing K x-rays. Nor is there a suggestion that these crystals can produce focused ion beams.1 8 Much of the current research attention and industrial use of these crystals is in low energy emission processes, infrared detection, sensitive temperature-change detectors and photonics. [9][10][11] There are interesting practical applications of pyroelectric crystal electron accelerators.…”

“…There is a voluminous literature on electron emission and production phenomena [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and plasma [22][23][24][25] formation at the surface of pyroelectric and ferroelectrics crystals. Reference 4, a recent comprehensive review article, is representative but does not suggest that pyroelectric crystals can produce focused, stable energetic electron beams capable of ionizing K electrons in high-Z materials and producing K x-rays.…”