Ion blaster is a mix of an ion wind blower and Van der Graaff generator. Ion wind blower acts as a brush of Van-der-Graaff generator that deposits charge onto belt, and the air stream is the belt itself.
Some of the charge carried by the jet will end up on surface the jet hits. This will charge the surface.
The fan is required, because ion wind is not strong enough to carry the charge. The ions will be electrostatically attracted back to the source, so the wind must be strong to counter ion drift thrugh the air due to this attraction.
The main purpose of Ion blaster is amusement. But there may be some interesting applications.
* ESD testing
* attaching sheets of paper and plastic to walls and other surfaces
* removal of dust and fumes from air
* triggering lightning strikes???