Interesting, because I thought it was another approach. So what's the power density calculation for this setup? Do any muons produce nuclear reactions other the hydrogen fusion?
From the data presented in the papers it seems far from reaching break-even just from the nuclear particle-induced electric signal, but I don't think optimizing the output has been the focus in any of these studies. The muons would interact in particular with heavy elements and the captured negative muons eventually produce unstable nuclei and neutron emission, so radiation shielding would be still required as Holmlid acknowledges here: https://www.tandfonline.com/do…080/15361055.2018.1546090
Holmlid Rydberg prehistory [1989] and electricity
I believe this was intended to work with the general idea that low-density Rydberg matter of alkali metals, in particular cesium, would have an extremely low work function and improve thermionic emission.
https://doi.org/10.1016/0039-6028(92)91335-9
https://doi.org/10.1016/0039-6028(93)90382-T
The much denser Rydberg matter of atomic hydrogen, required for producing the ultra-dense state, should not have such a low work function. Holmlid estimated a maximum value of 3.8 eV in https://doi.org/10.1016/j.susc.2008.09.007
As far as I understand the general idea is to obtain electricity directly from the nuclear reactions in ultra-dense hydrogen rather than thermionic emission: https://www.researchgate.net/p…n-ultra-dense-hydrogen-H0
It's still possible that a complete system could use both approaches, though.