I'm surprised the IEEE editors allowed the word "Introducing" in the title. Vacuum FETs are often a target of the diamond thin-film community. (Diamond has a very interesting electronegativity: Very little energy is required to get an electron out of diamond and into the "vacuum" (usually air.))
I'm no scientographer, but it seems to me that a dependence on helium may be a stumbling point for getting cheap vacuum transistors to the market. The ongoing helium shortage[1] is driving the price of helium up which could make helium-based vacuum transistors expensive, limiting widespread adoption. It could be that high-speed helium vacuum transistors become a speciality product for those projects that feel the need justifies the additional cost.<p>[1] <a href="http://www.decodedscience.com/helium-shortage-situation-update-one-year-later/42314" rel="nofollow">http://www.decodedscience.com/helium-shortage-situation-upda...</a>
Regarding the opening anecdote - some have suggested the Soviets used vacuum tubes so that their planes would survive the electromagnetic pulse from a nuclear explosion.
Oh that is pretty cool. I wonder if they have considered them as power switching devices. Something like that which had an effective Rds of nano-ohms could make electric cars more efficient.