Linnax railguns?

Hi,
  Just got finished reading book 3 of the Fifth Foreign Legion series
(Cohort of the Damned)....good book.

In the first chapter the aliens (Ubenfrarr) land on the planet surface
and
are trying to knock out the main planetary defense which is a linnax
railgun........can anyone give me a description of what this weapon is ?
 I
have a rough idea,but want to make sure.

Also what material is linnax? I have heard it used before at work but do
not
know what it is.....

Last, were there any  more books in the Fifth Foreign Legion series??

Thanks,

Mark D.