Speaker
Description
Particle accelerators are an invention of the early 20th century that have revolutionized our understanding of the universe and pushed the boundaries of our technological capabilities. These machines not only help scientists probe fundamental physics questions, but are also pillars in many industrial and medical applications. Acceleration of charged particles can be achieved by using superconducting radiofrequency (SRF) devices known as cavities, which apply variable electromagnetic fields to particles under cryogenic conditions. A key limitation to the performance of SRF based accelerators is contamination; external particulates (aka dust) present on the cavity surface trigger field emission, a phenomenon where electrons tunnel through the cavity surface due to strong electric fields. These rogue electrons limit the beam energy delivered to users and can even saturate machine protection systems. Field emission is actively observed at the TRIUMF electron linear accelerator (e-Linac); this accelerator shows a progressive onset of field emission in its SRF cavities throughout operation, despite cavities undergoing stringent cleaning procedures prior to installation. The reliable operation of particle accelerators is critical for the scientific and industrial applications of accelerator facilities worldwide, therefore understanding this phenomenon and its root causes is imperative.
My PhD work centers around the idea that particulates are actively generated by various accelerator components during operation, and migrate into SRF cavities after installation, leading to the increased onset of field emission. The dynamics of micron scale particulates in vacuum is influenced by their electrostatic charge, and the radiation environment of a particle accelerator provides an ideal opportunity for them to gain such charge. However, fundamental parameters such as composition and charge to mass ration of these grains remain largely unknown and are unique to each accelerator environment. I will present a series of experiments performed to study the charging and lofting of micron sized particulates in vacuum using an in-vacuum particle counter. The results of these experiments will shed light on the mechanisms that drive particulate migration and inform mitigation techniques to better maintain the performance of high energy SRF based particle accelerators.
| Keyword-1 | Accelerators |
|---|---|
| Keyword-2 | Reliability |