A Preliminary Study of the Effect of the Chirped Rotating Wall on a Positron Cloud

Abstract

The density of the positron cloud is a crucial parameter in many applications of accumulated positrons. Previous work has shown that adjusting the frequency of the rotating wall potential following positron accumulation can be used to control the density of positron clouds. In this work, positron clouds were studied after being compressed using a linear rotating wall frequency sweep under a selection of rotating wall drive amplitudes and cooling gas pressures following an initial static frequency compression. This was performed for SF 6 , CF 4 , and briefly for CO. The effect of changing the cooling gas appears congruent to that shown by the static frequency case. The results are in qualitative agreement with previous work by Deller et al., and compare briefly but favourably to a simplistic numerical model. i I suppose I will keep this brief. When I embarked on this journey of postgraduate study, my life, my home, and indeed the world was a very different place. Whilst the Covid-19 pandemic, which started shortly after my studies began has greatly effected me and my efforts and motivations, I cannot write this work and forget to mention my wife, Elinor, who has kept me sane these recent years. Since the start of these studies we have had many firsts, moving into a home together, getting married finally after pandemic-delay, getting a cat, and many others. Despite the rocky road however, the experiences, the knowledge I have attained, and the people I have met, are truly invaluable to me, and will remain so for the rest of my life. Finally, I must mention my late father. He was with me when I began my undergraduate degree and in many ways, he is still with me today.