Dear Axil, In pursuing an enhanced thermo-photovoltaic device at Draper Labs at the turn of the century, our group developed and utilized a computer code for optical coupling between surfaces. I noticed at the time that the code output included the force between the plates and that, when the optical emission exceeded the blackbody emission limit (by frustrated total internal reflection at fractional wavelength spacings of the plates), the force between the plates was repulsive. This was for thermally-generated emission of a randomly-polarized light spectrum; but, it could be tuned and enhanced by proper selection of material properties and thin-film coating thicknesses (see "Spectral selectivity from resonant-coupling in microgap-TPV," A. Meulenberg, K. P. Sinha for details).
arXiv:0911.0860 <https://arxiv.org/abs/0911.0860> This fits with the concept of the Casimir force ( https://en.wikipedia.org/wiki/Casimir_effect) by greatly increasing the wave-energy content between the plates over that on the outside of the plates. The effect is strongly temperature dependent ( https://en.wikipedia.org/wiki/Black-body_radiation#Stefan%E2%80%93Boltzmann_law); but, it is not limited to electrical conductors. (If the receiving plate surface is optically tuned to the selective emission of the "hot" plate, the force between them may become attractive instead of repulsive. I never checked on that detail of the model.) Since, as an engineering lab, we were application oriented, we did not look at the forces between the plates. We were concerned about developing a means of uniformly forcing two 2x2 cm flat plates together within a fraction of a micron without their making thermal-phonon contact. We lost our government funding (in 2005) and closed the internally-funded project down. It was spun off to become MTPV (https://www.mtpv.com/products/) and I retired to work on CF and other projects. If I had time, I suppose a reply to the paper in Phys Rev D would be appropriate. However, I'll write Bob Dimatteo, who was the project head at Draper and founder of MTPV Corp., to see if anyone still has that code. Andrew _ _ _ On Thu, Mar 21, 2019 at 6:26 PM Axil Axil <[email protected]> wrote: > The Casimir force can be tuned and even reversed by placing a chiral > optical material between two similar surfaces – according to calculations > by Qing-Dong Jiang <https://www.su.se/english/profiles/qjian-1.336861> > and Frank Wilczek > <https://www.nordita.org/people/staff/index.php?u=frank.wilczek> at the > University of Stockholm. The duo’s finding gets around a famous “no-go” > theorem, which says that the Casimir force between two similar surfaces > must always be attractive. The research could be of practical use because > the Casimir force can inhibit the operation of nanomechanical devices. > > > > https://physicsworld.com/a/chiral-material-reverses-casimir-force-say-physicists/ > > > Chiral Casimir Forces: Repulsive, Enhanced, Tunable > https://arxiv.org/abs/1805.07994 > >
