Franklin, R. N.Allen, J. E.Thomas, D. M.Benilov, M. S.2022-09-012022-09-012013-12-02Franklin, R. N., Allen, J. E., Thomas, D. M., & Benilov, M. S. (2013). Plasmas generated by ultra-violet light rather than electron impact. Physics of Plasmas, 20(12), 123508. DOI: 10.1063/1.4848715http://hdl.handle.net/10400.13/4546We analyze, in both plane and cylindrical geometries, a collisionless plasma consisting of an inner region where generation occurs by UV illumination, and an un-illuminated outer region with no generation. Ions generated in the inner region flow outwards through the outer region and into a wall. We solve for this system's steady state, first in the quasi-neutral regime (where the Debye length ${\lambda}_D$ vanishes and analytic solutions exist) and then in the general case, which we solve numerically. In the general case a double layer forms where the illuminated and un-illuminated regions meet, and an approximately quasi-neutral plasma connects the double layer to the wall sheath; in plane geometry the ions coast through the quasi-neutral section at slightly more than the Bohm speed $c_s$. The system, although simple, therefore has two novel features: a double layer that does not require counter-streaming ions and electrons, and a quasi-neutral plasma where ions travel in straight lines with at least the Bohm speed. We close with a pr\'{e}cis of our asymptotic solutions of this system, and suggest how our theoretical conclusions might be extended and tested in the laboratory.engPlasmasUltra-violet lightElectron impact.Faculdade de Ciências Exatas e da Engenhariajournal article10.1063/1.4848715