Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Field emission: the theoretical link between voltage loss, reduction in
  field enhancement factor, and Fowler-Nordheim-plot saturation   With a large-area field electron emitter, when an individual post-like
emitter is sufficiently resistive, and current through it sufficiently large,
then voltage loss occurs along it. This Letter provides a simple analytical and
conceptual demonstration that this voltage loss is directly and inextricably
linked to a reduction in the field enhancement factor (FEF) at the post apex. A
formula relating apex-FEF reduction to this voltage loss was obtained in the
paper by E. Minoux, O. Groening, K. B. K. Teo, S. H. Dalal, L. Gangloff, J.-P.
Schnell, L. Hudanski, I. Y. Y. Bu., P. Vincent, P. Legagneux, G. A. J.
Amaratunga, and W. I. Milne [Nano Lett. 5, 2135 (2005)], by fitting to
numerical results from a Laplace solver. This Letter derives the same formula
analytically, by using a "floating sphere" model. The analytical proof brings
out the underlying physics more clearly, and shows that the effect is a general
phenomenon, related to reduction in the magnitude of the surface charge in the
most protruding parts of an emitter. Voltage-dependent FEF-reduction is one
cause of "saturation" in Fowler-Nordheim plots. Another is a voltage-divider
effect, due to measurement-circuit resistance. An integrated theory of both
effects is presented. Both together, or either by itself, can cause saturation.
Experimentally, if saturation occurs but voltage loss is small (< 20 V, say),
then saturation is more probably due to FEF-reduction than voltage division. In
this case, existing treatments of electrostatic interaction ("shielding")
between closely spaced emitters may need modification. Other putative causes of
saturation exist, so the present theory is a partial story. Its extension seems
possible, and could lead to a more general physical understanding of the causes
of FN-plot saturation.

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The categories of this paper are: physics
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The categories of this paper are: cs
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The categories of this paper are: hep-lat
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: ao-sci
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol