http://www.spooky2-mall.com/ – Contact mode is not very effective for treatmemts for bone, head, lungs, or any other place that has high resistance to current flow. Plasma has no such limitations, and can easil reach these places.
Also, far field can run in the background and is more convenient. There is no need to remain in one location for treatment.
With all these things in consideration, contact mode is a better way of applying frequencies if the plasma tube is very far away.