Plasma
From what I understand they are experimenting with different "fills" besides sulfur -Lithium dioxide, copper dioxide & some "proprietary" chemical that one of the manufacturers is using to enhance the spectrum.
The plasma lamps supposedly have a really good lifespan -even better than LED's & have only lost like 1% over 50,000 hours. They also have no electrodes to detiriorate & no chemical reactions going on & can be started over and over with no loss of performance -no problems with hot starts, etc. With the LED looking like it will eventually be a viable alternative to HID for almost all lighting, including grow lights -the small amount of R&D into plasma lighting might not progress very quickly although it looks promising. The initial cost is high & the LED is progressing something like: double brightness and half the cost every two years -At that rate the LED could eventually be real competition for HID lights in greenhouse and indoor growing. The LED grow light industry has been damaged by inaccurate claims by manufacturers for so long that it may take a while for some of us to take the seriously.
Here's one of the rediculous claims from Everlight's GL Flora LED Grow Lights:
"Proven to grow faster and stronger than under sun light"
If that isn't a bunch of poop... Source=
It will be interesting to see what comes of Plasma lighting in the next decade (and LED too for that matter).
You can buy a Plasma grow light from Plasma International -500 to 1300 watts, 163,000 lm @ 140 lm/watt, air cooled -The lamp itself is the size of a golf ball! Has a microwave shield the size of a small coffee can.
Check it out here:
http://www.plasma-i.com/sulphur-plasma-light.htm
Watch the YouTube video too. I don't see a price on the page but I thought I had read somewhere that the AS1300 is $2500 (Ouch!) -A lot of loot but it sure would be a great conversation piece! And if it's not good for budding it would be nice for veg -starting out @ 500 & increasing to 1300W Grow some serious trees.
If anyone buys one of these be sure and post some results... It's a lot of money but probably a better spent $2500 than the everlight LED's would be!