I debated for a while if I should post this - but decided I had to.
I actually built a working IEC fusion reactor in my basement, back in 2005-2006.
I got to "first fusion" on Sept. 25th, 2006, and posted a video of the reactor
working, on Youtube. I just checked, and the video is still there.

https://www.youtube.com/watch?v=g18xpYXamAs

IEC (Inertia Electrostatic Confinement) fusion can be done, with a high-vacuum system, a high-voltage DC supply, and a vacuum-chamber with a high-voltage feed-thru. It is dangerous, but doable, and I believe I had the first working, amateur-built fusion reactor in Canada. One can confirm that fusion is occuring, by using sensitive chemical neutron detectors that workers in nuclear fission plants typically carry. I used BTI (Bubble Technology Inc.) detectors, which look like little test-tubes, and show small bubbles in a gel-like liquid, if exposed to a neutron flux.

My reactor was never able to produce more than 10^6 to 10^7 neutrons per second, which is a very weak neutron field. I used a small "lecture bottle" of non-radioactive deuterium (heavy hydrogen gas), and it worked well. I had to construct a deuterium injection system, using some high-vacuum valves, and a gas-feed-thru on one of the vacuum-chamber ports. The vacuum-chamber itself, and the high-vacuum diffusion pump (which used a mechanical vacuum pump, connected to a device which uses hot-oil vapour) and the high-voltage DC power supply, were all sourced from surplus equipment found on eBay, and imported from USA into Canada. The importation of each item was an adventure in itself.

One needs to put about 15,000 to 25,000 DC volts negative, on the confinement grid, and the vacuum chamber needs to be evacuated to about 10^-4 torr or better. I estimated the device needed mean-free path length of almost a 1 cm, for the D2 ion circulation, which is a very rarified environment.

What is really interesting about fusion, is how difficult it is to make happen. A palladium-wire grid would be better for the spherical confinement grid, but I used stainless steel. (Palladium is expensive, I had no source for it, and I am not Tony Stark...)

But the reactor did produce nuclear fusion events, using the D2 gas, and the high-voltage charge on the confinement grid. This technology was first invented and patented by Philo Farnsworth, an American researcher and inventor, who in the 1930's, invented electronic television. He invented the first electronic TV camera - the iconoscope - and fought with Sarnoff at RCA for years over the patent rights for electronic TV. Farnsworth's IEC fusion reactors also worked, but attempts to scale up the technology were not successful.

The various attempts at creating commercially viable fusion reactors are interesting. We keep getting close - but nothing that produces a useful level of net energy output, has yet to demonstrated, as far as I know.
I sincerely hope some sort of breakthru is possible, at some point.
My device - and most of the IEC devices - are able to produce a significant amount of neutrons, and research efforts at the University of Wisconsin, Madison, were able to demonstrate a powerful IEC reactor, which produced an intense neutron flux, sufficient to ablate the walls of the vacuum chamber (the chamber wall looked like swiss-cheese, under electron-microscope examination), so we know this technology is able to produce a serious amount of fusion events.

But taking this approach and using it to generate a net-energy output, has not been possible. My device was roughly 1500 watts in, and 1500 watts of heat out, plus maybe one or two extra milliwatts (or maybe a few hundred nanowatts). Not even enough to really measure.

I have followed all the various attempts to get some net useful energy out of fusion reactor technology, and I truly hope something becomes possible. We seriously will need this technology, and we are so close to having it. I wish all these researchers - public and private - the very best of luck.