Nano 8Gb

Recently, I purchased a Nano 8Gb thumb drive. Let us see how Linux responds to the device.
Below shows part of the System Log under Linux.



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Some information about Field Emission

I was searching through the net for some information and I came across this article.

Field Enhanced Emission

The current density in Thermionic-Schottky emission is weakly dependent on the magnitude of the applied electric field. Experimentally it is known that if the field is increased then a point is reached when the emission current starts to exceed the predictions of this theory. There are two models which may be used to explain this behaviour. First though we should discuss the Enhanced Electron Emission concept. If the field is increased above some finite level, then the width of the surface potential barrier becomes small enough that a considerable fraction of the electrons in the bulk material can 'quantum tunnel' through it. The number of electrons at or close to the Fermi energy (for cool metals (T less than T(Fermi)) in particular the bulk of the electrons exist just below the Fermi energy) is very much larger than at the high energies corresponding to the height of the surface potential. Therefore when the width of the barrier becomes such that these electrons can tunnel out, the emission current becomes very sensitive to the electric field. This field emission current quickly becomes much larger than the thermionic current. However the experiments indicate that this happens when the electric field strength is a few orders of magnitude less than theoretical considerations would indicate.

At this point we meet the two competing models: both are based on the concept of surface discontinuities

i) The difference between experiment and theory can be explained if one assumes that on the surface of a cathode, micron sized discontinuities having the form of an outward spike exist. If the length of the spike is>10 times its base dimension then it is relatively easy to expect the local electric field to be enhanced by a considerable amount (> x1000). Then the theoretical model discussed above applies to the surface of the discontinuity. It is interesting that the enhanced emission current from a handful of such micron sized sites can exceed (by many orders of magnitude) the total thermionic current from the bulk cathode at sufficiently high electric fields. Such discontinuities have been observed on real cathode surfaces, and in some experiments at the University of Strathclyde specially manufactured Field Emission Arrays consisting of millions of such individual tips machined in a semiconductor surface have been used as a source of a high quality, highly controllable, electron beam.

ii) The other model is based on the assumption that the onset of Field Enhanced Emission at such a low electric field can be attributed to insulating inclusions (micron sized) in the cathode surface. Electrons emitted from the bulk cathode into the conduction band of the insulator are accelerated towards the vacuum, collisions with electrons in the valance band of the insulator cause an 'avalanche' of electrons. In this model it is assumed that electrons are emitted from the insulator by the thermionic process and the temperature is described in terms of the electric field that has accelerated them through the insulator. This yields a close match to many experimental measurements of Field Enhanced Emission.**

**R.V. Latham, 1983, "Prebreakdown Electron Emission", IEEE Trans. on electrical Insulation, EI-18, pp194-203

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Doing Good Deeds

Good Deeds

Put your utmost effort into doing good deeds and do not slack. Print more virtuous books and distribute them.

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