In addition to R.B. Ridley’s model, the current programmed controller model introduced by R. W. Erickson also is very popular. The inductor current waveform is illustrated in Figure 4. 4.

LTspice includes a set of proprietary Special Functions/mixed-mode simulation devices generally used to create simulation models. See LTspice Help Special Functions. The Sample device is one of the ...

So far, so good. If you look at the peak output voltage and current, you’ll see the load sees 50V (half of the source) and, of course, with a 50-ohm load, 1A of current for a total of 50 watts.

[Mano Arrostita] has a video about simulating delay and timer circuits in LTSpice. The video isn’t specifically about the 555, but it does show how the basic circuits inside a timer chip work.