The classic example of an IEC device is a fusor. A typical Fusor has two spherical metal cages, one inside another, in a vacuum. A high voltage is placed between the two cages. Fuel gas injected. The fuel ionizes and is accelerated toward the inner cage. Ions that miss the inner cage can fuse together.
Fusors are not considered part of the CBFR family, because they do not traditionally use beams.
There are many problems with the fusor as a fusion power reactor. One is that the electrical grids are charged to the point where there is a strong mechanical force pulling them together, which limits how small the grid materials can be. This results in a minimum rate of collisions between the ions and the grids, removing energy from the system. Additionally, these collisions spall off metal into the fuel, which causes it to rapidly lose energy through radiation. It may be that the smallest possible grid material is still large enough that collisions with the ions will remove energy from the system faster than the fusion rate. Beyond that, there are several loss mechanisms that suggest X-ray radiation from such a system will likewise remove energy faster than fusion can supply it.