Phosphor Aging in P39 Tubes

P39 phosphor exhibits a long-persistence green emission that ages predictably under continuous excitation. The aging curve is roughly logarithmic for the first thousand hours and approximately linear thereafter.

A tube held at constant beam current loses roughly 8% of peak luminance per thousand hours. Operators should recalibrate brightness at the 500 and 1500 hour marks and substitute the tube at 4000 hours.