We establish that the extended Robba rings associated to a perfect
nonarchimedean field of characteristic p, which arise in p-adic Hodge theory as
certain completed localizations of the ring of Witt vectors, are strongly
noetherian Banach rings; that is, the completed polynomial ring in any number
of variables over such a Banach ring is noetherian. This enables Huber's theory
of adic spaces to be applied to such rings. We also establish that rational
localizations of these rings are principal ideal domains and that etale covers
of these rings (in the sense of Huber) are Dedekind domains.Comment: v3: final refereed versio