Nope. It's not sulfur plasma, indeed it is based on Metal Halides, not sulfur. Sulfur plasma lamps usually have large spinning balloons and are available mostly in very high output (usually >700W), which makes it very hard to distribute if you don't have much ceiling height. They are bulky, noisy and not solid state. The beauty of LEP by Luxim is that there are no moving parts. So yes it is plasma technology which gets it's wide spectrum from molecular emission (but not from sulfur but from metal halides, it has much more UV than sulfur plasma), is generated in an electrode-less cell heated by a tuned microwave (though stationary instead of rotating, and very small) and it also has a very long life. They call it LEP - Light Emitting Plasma. It is a sort of HID lamp (high intensity discharge lamp) but without electrodes and arc to heat the metal salts in the HPS/MH arc tube.
The HPS and MH lamps are based on atomic emission, not molecular emission. Every specific element has its specific emission line, specific colors in the spectrum. Sodium has a narrow transmission line you see really well in a low pressure sodium lamp. In a high pressure sodium lamp that spectrum is widened. So unlike plasma light (which is molecular) it is much more difficult to get a wide and even spectrum. Metal halides are a much better for spectrum but they lose material inside the arc tube so they tend to wear out fast and lack in color stability. Ceramic arc tubes don't permit those losses so they are much more stable in color and light maintenance.
Most LEP fixtures on the market use the LUXIM STA series emitter. There was (and still is) the STA 40 series, which is universal position (looks like a led in the center of the round puck) and there is the STA 41 series designed for pointing downward +/- 90 degrees (though we recommed +/- 60 degrees). It has a square puck and the cell is horizontally embedded. It has about 25% better efficiency than the STA 40 series. On the Gavita website you can find the two different spectra. Also check the whitepapers in the download section for for explanation about the spectra and the use of it supplemental light for HPS.
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