Is MH ceramic, discharge or both? I'm just puzzled as I've seen a MH use some ceramic arc tube and a normal discharge tube.

Is HPS discharge as well, due to the arc tube?

Both, the ceramic version was the latest tech until LED replaced them, they’re kind of like a halide version of HPS, but without sodium.
HPS, mercury and MH are all discharge lamps.

No matter the arc tube material, HID lights (including MV, HPS, and MH) are discharge devices.

“Arc tube” and “Discharge tube” are two words for the same exact thing: the little container that the gas discharge is in. Discharge tubes can be made with a variety of materials including glass, quartz, ceramic, sapphire, and probably some other materials that I am missing (depending on the specific type of lamp)

Metal Halide is a discharge-based lighting technology (specifically HID). They are made in both quartz (“normal”) and ceramic discharge tubes.

HPS is also a discharge-based lighting technology (Also specifically HID). These were mostly only made with ceramic discharge tubes, but sometimes sapphire.

Mercury vapor, fluorescent, neon tubes, etc, are also discharge-based lighting technologies, some are HID and some are not, and many different discharge tube materials are used. The material of the discharge tube has nothing to do with whether it is a discharge-based technology or not.

Hope this helps!

MV, all MH's, HPS are all high pressure arc discharges, where an electric arc in a gas mixture generates light.
The name suggest the active materials responsible for generating light when excited in the arc (Mercury and Sodium are selfexplaining, MH means mixture of metals and it suggests they are used in the form of halide salt compounds)


The "ceramic" vs "quartz" is refering to the material of the arctube - the pressure vessel holding the typically high pressure (few atm, till few 10's atm in some MH's) gasses contained around the arc and which then needs to pass the generated light out. Quartz is plain transparent, the ceramic, usually polycrystaline alumina, is translucent (the grains diffuse the light).

So in theory you could fabricate a discharge lamp using any combination of arctube material and principal gas composition, it will work, at least for a short time.
But some would be unnecessarily expensive (e.g. ceramic MV), or have corrosion problems (atomic sodium readily reacting with/diffusing into the quartz and forming opaque material out of it). Or the limitations related to ceramic manufacturability would mean you can not use starting probes, so ceramic lamps are either pulse start or designed so the ballast OCV ignites them with just the main electrodes there (some special HPS intended as MV retrofits).

So in real life MV's are made exclusively using quartz as the material for the arctube,

HPS are exclusively using ceramic arctubes,

MH you find in both variants, but each needs to have different fill composition, tailored to utilize the benefots of each material and somehow make up for its drawbacks.
Ceramic allows more freedom so allow better color quality at higher efficacy, but are more expensive and because the alumina tends to dissolve in salts, suffer from shorter lifetimes.
Quartz MH's suffer from lower efficacy and color quality (although the latest MH development was able to somehow improve that and reduce the gap towards ceramics), but are cheaper and longer lasting.

I don't believe ceramic arc tubes suffer from shorter life (even at higher power loadings) compared to quartz ones. Can you cite some datasheets for comparable lamps (like 150W ceramic Philips vs 150W quartz Philips) to demonstrate this?

It is true, the CMH mortality is at some point in development an engineering trade off compromise selection between efficacy (thinner arctube absorbing less light) vs life (thicker arctube, so it takes longer to penetrate; assume all the rest is the same)
At one point (true, quite early after the CMH came to the market) use to be rated 12k (quartz) vs 9k (ceramic) hours. But agree, given the statistics, it is barely any real difference (the statistical uncertainty is just wider than that difference)...
But it is true at that point the quartz were very mature products, but the ceramics were rather new thing on the market.
Did not study these things anymore after that...

If I remember right, later cylindrical burner CMH were rated at 12000 hours. Last 70W CDM Elite datasheet of year 2024 states 20000 hours to 50% survival, though on an electronic gear.

See this interesting appnote on MH lamps, particularly it explains classic CMH failure mode and how rounded burners fixed this.

https://www.ledvance.com/00_Free_To_Use/asset-300284_Metal_halide_lamps._Application_guide_V1.pdf