Where did the technology of Stanislav Adamenko and the Ukrainian Proton 21 lab go?

Simple answer, the US.

Along with all patents granted and pending. Connection was made after finding authors in this paper published in Results in Physics, Volume 5, 2015, Pages 62-68

They are working to develop a 'electron beam' fusion reactor. From their site they say:-

"Our pulsed-power generator, nicknamed “Thunderbird,” can create a super-concentrated burst of power strong enough to create the conditions necessary for fusion to occur. These power bursts are focused on microscopic targets via an electron beam, and our initial tests of Thunderbird indicate the device can produce more than 12 billion watts of power. This enormous power invested into such a small volume using only a minimal amount of hardware revolutionizes the whole approach to fusion power generation.

The design and efficiency of Thunderbird allow us to move forward very fast on the path toward creating a commercially viable power generator that produces energy via fusion."

Figure 1: Relativistic Electron Beam Pulse SOURCE

And, to some that recognise the name, George Miley is Scientific Consultant and Advisory Board Director.

Further reading

Paper | History | Technology | WEBSITE