Effect of impacts on planetary atmospheres

This is some new work that I'm developing at the moment, which consists in studying the effect of impacts on planetary atmospheres. We know that they are comets in our Solar System and exocomets in extra Solar Systems are now detected. It is thus fair to want to know what happens to a planet's atmosphere when it is impacted by a series a comets over its lifetime. We developed a new generic method to work out if a planet's atmosphere is more likely to be enriched in volatiles from impacting comets or rather be destroyed and stripped little by little owing to impacts. We first apply our new model to the TRAPPIST-1 system, which possesses 7 planets. We find that if the TRAPPIST-1 system has a belt of debris (throwing comets at a rate at least similar to our Kuiper belt), then a potential primordial Earth-like atmosphere would be destroyed on the 7 planets and only the outermost three planets f, g, and h would be able to be replenished from volatiles delivered by impacting comets. Hence, we expect the atmospheres of planets f, g, and h to be more massive than for other planets in the system.