[ChuckMcM]

And to be clear, the time it takes for a phosphor dot to go from "off" to "full bright" to "off" again is its frequency response. And every dot of phosphor has to be "visited" by the electron beam on every frame. With those two numbers you can get the absolute fastest you can scan through the dots with full dynamic range.

In the CRT designs we looked at in college they typically used a fixed "dwell time" of the beam, so it was on each pixel for a fixed amount of time, and modulated drive power to get different intensities. (some phosphors are non-linear in their response so you can correct that in the drive table).

And as I was reminded in email, the beam has to visit every pixel AND get back to the top of the screen for the next frame. So on a 480i screen that is 640 x 240 per frame at 30Hz, that is 30 frames per second / 640 * 240 pixes per frame so you have just 195 uS to spend on each pixel. (less than that actually since with overscan you have 720 pixels per line but it is a very short time).