Niobium is ductile and strong, properties needed for ease of cavity fabrication. Despite the material's advantages, however, manufacturing inevitably leaves behind a thin layer of dust and debris, which degrades performance. Prior to installation, cavities are therefore routinely cleaned and polished chemically, in an acid bath. Nevertheless, this process isn't able to remove all surface contaminants. So Laboratory specialists have developed a technique known as helium processing.
Helium processing involves injection of helium gas directly into the cavities.
When RF power is applied, contaminant particles are heated and spray out electrons, ionizing the helium. Helium ions then backscatter into the contaminant particles, destroying them. Eventually the particles burn themselves out. Jean Delayen, head of the Accelerator Development Department, says the goal is to improve future cavity performance three-fold, but with no increase in the cost per module. The analyzer will send radio frequency waves through the cavity as part of the cavity tuning process.