things they did in the 40,50's

[pallophotophone]

Good Point, The browning I've seen relative to phosphor burn in projection CRT's is always a raster shaped pattern as opposed to the spot in the middle. I once heard of a
RCA theater projection system which had such high beam currents that if the tube lost sweep, the electron beam would cause the tubes face to be cut and fracture until the vacuum was compromised. This used a stock Westinghouse brute force high voltage power supply sutible for use with X ray gear. 80 kv at 135 ma if memory serves.