Electron stimulated gas desorption from copper material and its surface analysis

Abstract In the KEKB accelerator that is a two ring electron–positron collider, the vacuum chambers were mainly made of oxygen free copper (OFC). To obtain quantitative data on outgassing from the copper surface irradiated by energetic particles in systems such as particle accelerators and plasma based devices, we focused on a measurement of electron stimulated gas desorption (ESD) from copper materials. Four different samples were prepared to make comparison, that is, as-received, treated with sulfuric acid and hydrogen peroxide (SH), treated with citric acid (CT) and treated with SH+CT. In order to quantitatively measure the ESD rates from those surfaces, a throughput method was used with a calibrated RGA. Surface characterization of those samples was also done by Auger electron spectroscopy (AES) with sputter etching. According to the results of AES depth profiling and the ESD yields, the treatment with SH proved to be the most promising property.