I bought this piece from a certain J B Stevens. He has, in my opinion, one of the best Trek Collections in the world, and can be found here http://startrekpropcollector.com/ A number of my pieces came from him, and I owe him a lot!!!
This piece also came with a COA from IAW, and can be seen in various episodes such as ;
(VOY: "Dark Frontier")
(VOY: "Think Tank)
(TNG : High Ground)
Here is a link to all things Plasma charge http://memory-alpha.org/wiki/Plasma_charge
I think there are three of these doing the rounds, I won this one, and one came up at the recent PIH auction.
Here is a pic of my charge. It fully lights up my means of a switch on top, with lights on the side and a blinking light on top. Its made of very strong material and is quite substantial.
And here it is being used in the TNG Episode: The high ground.