Jim Kelley wrote:
But in
consideration of the latter, it should be apparent that if the magnitude
of the randomly fluctuating ion current approaches that of a small
electromagnetic current it would be impossible not to detect it.

Exactly. Whether one particle can cause a detectable noise
pulse obviously depends on the charge on the noise particle
and a number of other parameters.

But given, e.g. a coax fed dipole with the coax braid grounded,
a difference is charge is likely to occur between the elements
that is large enough to be heard.
--
73, Cecil http://www.qsl.net/w5dxp