Hm? They are definitely not cold fusion.
Cold fusion really means room temperature fusion, but achieving it and making it practical is quite dubious for reasons of fundamental physics. Atomic nuclei are positively charged and hence repel each other. So to get them to fuse they basically need to come together very fast. In quantum mechanical terms, they must have enough energy to have a non-negligible probability of tunneling across the Coulomb barrier. So the conditions for fusion are calculable and pretty well understood. When Pons and Fleishmann claimed in the 80s to achieve it at room temperature, it received much media sensation, but to physicists did not seem very credible, and attempts to replicate their experiment failed to show an effect. It's much like the EMdrive claims over the last few years.
So, fusion requires a lot of kinetic energy per particle. There are many ways to do it. It can happen in a very high temperature plasma, which may be magnetically confined (like the Tokamak design). Or it can be achieved by shining intense lasers at a small target, heating and compressing it. Or it can be achieved in certain nuclear weapons by compressing the material first in the detonation of a fission weapon (a good way to get fusion to happen, but not a good way to power a city.) Finally, it's possible to achieve fusion even at home (with much effort and technical knowledge) by accelerating ions through a strong electric field into a target. That is the "fusor" design, and there is a community of hobbyists who build them
. This manner of fusion is not a good way to get more useful energy out than you put in, but it can be a neat tabletop physics demo, and is also a neutron source. The detection of those neutrons is the proof that the fusion is occurring.
The most promising way I know of so far to turn out a gain from fusion is probably through some manner of magnetically confined plasma, and the difficulty is really in how to get the energy out of the reaction efficiently without compromising the reaction or the vessel containing it. But I like to think that we already have useful fusion energy, from the Sun. Nature provided the reaction already. Gravity contains it, hydrostatic equilibrium moderates it, and the output energy falls on Earth constantly. Put up a solar panel, and you literally harness fusion power. The dream of fusion reactors is not so much to get energy from fusion processes, but to obtain much more than 1300 watts per square meter of area.