High-performance double-ended CMH lamp

Here's an unusual one: a nonstandard compact double-ended metal halide lamp fitted with Philips's 70 W CDO Plus burner. This ceramic MH arc tube has a fill chemistry optimized for an operation on conventional 70 W HPS ballasts, intended for outdoor lighting applications (mostly the retrofit of existing sodium lamp systems). This lamp type differs from standard CMH ones by a higher sodium dosage, which results in a warmer light color (2750 K), and a lower argon fill pressure, which reduces the ignition voltage requirement to that of 70 W HPS lamps (i.e., 2.5 kV). Moreover, the Plus variant -which is the 2nd-gen CDO platform- features a shaped isothermal burner filled with a high-efficiency cerium-based salt mix, which raises the lumen efficacy just past 100 lm/W. CDO lamps are peculiar for the fact that they deliver high (initial) performances while not requiring an electronic control gear for their stable operation. The downside is a slightly faster lumen depreciation rate than that of standard high-performance warm-white CMH lamps such as the CDM-T Elite in /930 color. In the present case, with the compact double-ended jacket, the burner operates at a higher-than-normal temperature, which pushes the efficacy to 106 lm/W, while the light color temperature is raised to 2910 K with a CRI exceeding 90 Ra8. The trade-off, however, is a faster degradation rate of performances and a shorter service life. This lamp was made over a decade ago for testing purposes and was never released on the market.