sorry for bumping but plasma lights have evolved over the years. Luxims LEP is a solid state technology, no more moving parts. I demonstrated them to Shanti and Howard at the Spannabis, he has already seen them at work at flowery field in Austria where they have dramatically improved their cuttings production with plasma lighting.
It is quite simple:
The sun alike spectrum of 300W LEP is great for vegetative growth, nothing beats it there. For generative development you need more efficient red (and infrared) that the HPS is providing much more efficiently (HPS hardly makes any blue photons). HPS is up to 2 micromoles per Watt, plasma is 1 micromole per Watt. The combination of plasma and HPS in flowering keeps your plants green and healthy (right until the end), influences the morphology of the plant, initiates earlier trichome development and enhanced the flavonoids and terpenes in the plant. There are many grow reports available on the net already.
If you look just at yield, you can easily calculate that, by light only, a plasma unit pays back within 2 grow cycles and I am not even counting quality there. Let's face it: We don't grow lettuce under these lights
.
compare it to a greenhouse: in order to grow healthy plants you need sunlight. When you do not have enough sunlight you
add HPS, which is the most effective lamp for making photons. A common rule in greenhouses is that you need at least 5-10% of blue light. Indoor you obviously do not have sunlight, you can add that with a plasma unit.