How does the raster scan frequency affect the accuracy of a CRT TV picture?

[tech99]

I couldn't find any information on this but I do wonder, what was the average CRT raster scan line thickness in terms of pixels illuminated in each full scan from left to right?
Did the electron beam illuminate a line that is just a single pixel width on each pass or did it hit multiple pixel width as it passed along the screen?

My own guess would be that those were multiple pixels widths on each scan line because if we take interlaced picture as an example at 50hz frequency then there were 25 odd and 25 even lines drawn on the screen each second, but the way I see it I can't imagine that if each line was a single pixel width it would be capable of covering the whole screen area.Oh and while I am at it, I'm sure someone here like @sophiecentaur or others could answer this one also.
So the raster scan frequency of 15..something Khz was chosen to be in correlation to the vertical refresh rate frequency because in order to draw an accurate picture the electron tube's 3 individual color gun grid's need to change their potential so that within each scan line brighter pixels get more electrons while darker ones get less, so I suppose the color gun accelerating electrodes were directly driven by the video signal circuitry but in order for this to make an accurate picture the raster scan had to be fixed rather precisely in order for the beam to match each pixel in the required intensity, so far correct?

If this is correct then how did the CRT cathode-anode high voltage effect this picture accuracy?
From what I have experienced myself and seen is that increasing or decreasing this main accelerating voltage makes the whole screen and picture brighter or darker but doesn't the accelerating potential also change the speed of the electrons in the beam so that at the same raster scan frequency the electrons now would arrive at the screen mask and pixels later and hit the wrong pixels?
Or do minor changes in accelerating potential doesn't affect the electron speed in vacuum by much?

A monochrome TV screen is not made up of pixels, but is continuous.

 

[artis]

@tech99 a black n white screen yes but i was referring to a color screen

I tried to find any field line presentations from a deflection yoke but can't find any.
It seems like each yoke had two coils that were similar to ordinary pole coils being straight for the longer part and oval at ends and then it has this toroidal shaped ferrite with a winding around it.
although it's rather hard to imagine what the fields were like.

 

[sophiecentaur]

The purpose of interlacing was to reduce flicker.

The main purpose / great advantage of interlace is that it improves Motion Portrayal. It would be easy enough to introduce some 'extra' flicker as with the rotating Maltese cross screen in movie projectors which does reduce flicker but doesn't eliminate the jerky motion. A 25/30 Hz picture rate causes very jerky motion portrayal. The 50/60 Hz field rate that interlace provides a significant improvement - it's almost the same effect as doubling the temporal sample rate in a very significant point in the spectrum of moving images. The downside is pretty minimal. Yes, the lines appear to creep down the screen but at 'Five times Picture Height' (the recommended viewing distance for 625 line TV) you can't actually spot that. None of that is relevant once you up convert in the receiver and provide motion interpolation.

A monochrome TV screen is not made up of pixels, but is continuous.

Well . . . . . . It does have exactly the same vertical 'pixellation' that you get with a 2D sampled image. The continuous coverage of the monochrome phosphor is a different issue and Pixels are not inherently associated with phosphor dot spacing and sizes.