Electron Drift Velocities in Liquefied Argon and Krypton at Low Electric Field Strengths

Abstract An induced impurity photoconductivity by the electric field, thermally stimulated conductivity and spontaneous pulsations of the dark current were found in the undoped (with a dark resistivity P77≈3•104÷108 Ω-cm at T≈77 K) and erbium doped (NEr=10–5÷10–1 at.%) p-GaSe crystals in the temperature range of T≤240÷250 K at electric field strengths (E) creating a noticeable injection. It was found that the value of the observed impurity photoconductivity (M) monotonically increase at low illumination in undoped crystals with increasing P77 and its spectrum smoothly expands towards longer waves. The value of ∆ii and the width of its spectrum change non-monotonically with increasing NEr in doped crystal and it gets its maximum value at NEr ≈5•10-4 at.%. The intensity of spontaneous pulsations increases with increasing E at the higher electric field strengths. However, the impurity photoconductivity and the peak of thermally stimulated conductivity gradually disappeared. The amplitude and frequency of the observed spontaneous pulsations of the dark current is increased with increasing in the injection ability of the contacts. Moreover, the pulsations of the dark current gradually disappeared with increasing T. It was shown that all these three phenomena are directly caused by the recharge of sticking levels with a depth Er ≈+0.42 eV and a density Nt≈ 1015 cm-3 by injected holes. However, in high-resistance undoped and doped Er ≤10-2 at.% crystals, it is also necessary to consider the presence of random macroscopic defects in the samples to explain their features. A qualitative explanation is proposed based on the obtained results.

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A 4 × 4 array multichannel magnetic stimulation system using submillimeter sized planar square spiral coils: The spatial distribution of electromagnetic field

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-210139 ◽

2022 ◽

pp. 1-18

Author(s):

Lei Tian ◽

Limei Song ◽

Yu Zheng ◽

Jinhai Wang

Keyword(s):

Magnetic Field ◽

Electromagnetic Field ◽

Spatial Distribution ◽

Field Strength ◽

Electric Field ◽

Magnetic Stimulation ◽

Spiral Coil ◽

Average Magnetic Field ◽

Stimulation System ◽

Field Strengths

Multi-coil magnetic stimulation has advantages over single-coil magnetic stimulation, such as more accurate targeting and larger stimulation range. In this paper, a 4 × 4 array multichannel magnetic stimulation system based on a submillimeter planar square spiral coil is proposed. The effects of multiple currents with different directions on the electromagnetic field strength and the focusing zone of the array-structured magnetic stimulation system are studied. The spatial distribution characteristics of the electromagnetic field are discussed. In addition, a method is proposed that can predict the spatial distributions of the electric and magnetic fields when currents in different directions are applied to the array-structured magnetic stimulation system. The study results show that in the section of z = 2 μm, the maximum and average magnetic field strengths of the array-structured magnetic stimulation system are 6.39 mT and 2.68 mT, respectively. The maximum and average electric field strengths are 614.7 mV/m and 122.82 mV/m, respectively, where 84.39% of the measured electric field values are greater than 73 mV/m. The average magnetic field strength of the focusing zone, i.e., the zone in between the two coils, is 3.38 mT with a mean square deviation of 0.18. Therefore, the array-structured multi-channel magnetic stimulation system based on a planar square spiral coil can have a small size of 412 μm × 412 μm × 1.7 μm, which helps improving the spatial distribution of electromagnetic field and increase the effectiveness of magnetic stimulation. The main contribution of this paper is a method for designing multichannel micro-magnetic stimulation devices.

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Electric-field strengths measured near personal transceivers

1993 International Symposium on Electromagnetic Compatibility ◽

10.1109/isemc.1993.473783 ◽

2002 ◽

Cited By ~ 1

Author(s):

J. Adams

Keyword(s):

Electric Field ◽

Field Strengths

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Electric field measurements on Cluster: comparing the double-probe and electron drift techniques

Annales Geophysicae ◽

10.5194/angeo-24-275-2006 ◽

2006 ◽

Vol 24 (1) ◽

pp. 275-289 ◽

Cited By ~ 45

Author(s):

A. I. Eriksson ◽

M. André ◽

B. Klecker ◽

H. Laakso ◽

P.-A. Lindqvist ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Cold Plasma ◽

Field Measurements ◽

Low Energy ◽

Electron Drift ◽

Double Probe ◽

Flow Energy ◽

Potential Control ◽

Spacecraft Potential

Abstract. The four Cluster satellites each carry two instruments designed for measuring the electric field: a double-probe instrument (EFW) and an electron drift instrument (EDI). We compare data from the two instruments in a representative sample of plasma regions. The complementary merits and weaknesses of the two techniques are illustrated. EDI operations are confined to regions of magnetic fields above 30 nT and where wave activity and keV electron fluxes are not too high, while EFW can provide data everywhere, and can go far higher in sampling frequency than EDI. On the other hand, the EDI technique is immune to variations in the low energy plasma, while EFW sometimes detects significant nongeophysical electric fields, particularly in regions with drifting plasma, with ion energy (in eV) below the spacecraft potential (in volts). We show that the polar cap is a particularly intricate region for the double-probe technique, where large nongeophysical fields regularly contaminate EFW measurments of the DC electric field. We present a model explaining this in terms of enhanced cold plasma wake effects appearing when the ion flow energy is higher than the thermal energy but below the spacecraft potential multiplied by the ion charge. We suggest that these conditions, which are typical of the polar wind and occur sporadically in other regions containing a significant low energy ion population, cause a large cold plasma wake behind the spacecraft, resulting in spurious electric fields in EFW data. This interpretation is supported by an analysis of the direction of the spurious electric field, and by showing that use of active potential control alleviates the situation.

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Spatial profiles of metastable densities and electric field strengths in parallel-plate radio frequency discharges

IEEE Transactions on Plasma Science ◽

10.1109/27.491742 ◽

1996 ◽

Vol 24 (1) ◽

pp. 121-122 ◽

Cited By ~ 1

Author(s):

G.A. Hebner ◽

K.E. Greenberg

Keyword(s):

Electric Field ◽

Radio Frequency ◽

Parallel Plate ◽

Radio Frequency Discharges ◽

Field Strengths

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