The image to the left is Hyperion.
What i'd like you to focus on are only those craters
that have formed squarely on the rim of a larger crater.
These craters were most likely formed during a large
EDM sculpting episode and within the same timeframe.
They differ only slightly from the rim features being
considered in CRT experiments yet should not be confused
with overlapping crates that occur at
widely seperated timeframes.

Look at these images real close to see the rim craters. But don't confuse an overlapping crater( not crater chains either) with the rim craters i'm focusing on which are substantialy smaller than the host crater.

The angle at which you look at these images is critical. If you are using an LCD screen tilt it until the LT-green backgroung is very light. If the green background is near to medium green lighten your screen.

Copy the image to your system so you can manipulate its size.

  In the images below You will several types of craters that have formed in contact with an adjacnet crater. In the left image's large crater chain all those craters were made on the same pass, except the faint ones on the left, mid way along the chain. So, from this we might be able to conclude that some rim craters are formed as an ongoing series of discharges preferentially tags an accumulation of material around the perifery of a larger discharge feature. This is not to say that the discharges are continuous or sustained in the manner or environment which sculpts comets and asteroids. You'll see the same in the crater chain near the left edge in the right image.

  If you look to where, on the rim, these rim craters form we may gain some insight into the discharge. If you look real close you see that most occur on the outside edge of the rim and not squarely on the rim. This leads me to think that the surface beyond the larger discharge is what the interaction was focused towards so this may bring these rim craters back closer to the primary chain discharge, and not an isolated event, the difference being in the available energy for an exchange at the location. [Keep in mind that the material of these CRT discharges is coming off the CRT surface and is crusted to the probe (my finger in this case).] As the probe moves further along the path a much larger discharge occurs to form another primary crater in the chain, so i've concluded that the surface potential is the principle facter in the discharges and that a limited amount of discharge to the probe can be expected at any given point. Returning to the area around a point of discharge will only result in a discharge to an unaffected area. I recall that during these experiments i attempted to get discharges with a previous discharge but could only get an adjacent discharge that would not involve the rim of the former crater-like feature.