The presence of the rings could certainly have a dampening effect on the radiation belts at Saturn, when compared with Jupiter. Interestingly, I'm currently working on a study that attempts to measure the effect of the radiation belt of Jupiter on the ionosphere - it has been invoked numerous times to explain increased emission towards the equator, but my recent studies of the nightside of the planet have suggested its effect is limited.

We are certainly measuring emission from Uranus, but it is so far away, that it's difficult to get enough signal to say much of anything about the ionospheric variability. It would certainly be interesting to attempt to look at whether this would have an effect at Uranus. The Uranian rings are much less massive, though, so I tend to believe the effect would be less pronounced too.

To be honest, we really didn't expect to find it at any of the planets. It was proposed as a theory, with some evidence, at the time of Voyager, but has been relatively ignored since that time. Certainly, we would have looked for this effect at Saturn, if we'd thought it was a likely process, but in addition, the H3+ emission we measured in the paper is very weak. The first detection on the body of the planet was only last year, and it was only though the use of Keck, with its giant bucket-like collecting capabilities, that we were able to get a strong enough signal that we could even attempt to measure this effect.