Gridded ion sources: Is there RF leakage to grids? Let's take a look at a simplified image below showing typical 3-grid RF ion source construction.
On the practical side - I would assume that some of RF excitation energy will be picked up by grid(s) as antennas, and without special tricks bias power supplies might be in an uncomfortable spot being back-fed with 10-100W of RF power.
Is this a common/known issue for RF ion sources and is there a solution to this?
Image from https://epjd.epj.org/articles/epjd/abs/2015/10/d150380/d150380.html?mb=0 :

 A: There are several papers with open access and with nice explanation of RIT design and operational principle such as
Development of the Radio Frequency Ion Thruster RIT XT – A Status Report by Hans.J. Leiter, Rainer Killinger, Helmut Bassner, Johann Müller, Ralf Kukies,. 2001, IEPC-01-104.
Radio Frequency Ion Thruster – Radio Frequency Generator, Power Supply, and High Voltage Converter, by Anton Lebeda, Arnold Lebeda. Trudy MAI, 60, 2012.
Evolution of the AIRBUS DS GmbH Radio Frequency Ion Thruster Family by H. J. Leiter, Ch.Altmann, R.Kukies, J.Kuhmann, J.-P. Porst,  Joint Conference of 30th International Symposium on Space Technology and Science 34th International Electric Propulsion Conference and 6th Nano-satellite Symposium,Hyogo-Kobe, Japan, July 4 – 10, 2015.
Global models for radio-frequency ion thrusters by Patrick Dietz, Andreas Reeh, Konstantin Keil1, Kristof Holste1, Uwe Probst, Peter J. Klar and Chris Volkmar, EPJ Techniques and Instrumentation (2021) 8:10, here
The model of RIT described in the last paper consist of Poynting’s theorem in the form (see equation 14 in the paper cited)
$$\frac{1}{2}I^*V =\frac{1}{2}\int\int\int(kE^2-i\omega/\mu_0 B^2)dV$$
There is no radiative term in this equation and authors explain it as follows
"Radiative processes are neglected, which holds true due to comparably low frequency (i.e. large wavelengths of about 100 m) and short conducting structures which do not form any kind of waveguide."
