About the MeVVA:

MeVVA stands for MEtal Vapor Vacuum Arc. The MeVVA is used to inject metal ions into the ion trap region. MeVVA utilizes vacuum arcs to create the metal ion plasma. The basic process of MeVVA is shown here. With our current MeVVA setup, we can usually produce ions (~efficiently) continuously for about 12 hours. After this time period, the trigger-cathode insulator usually becomes "plated" by the cathode material. At this point, there is a conducting surface between the trigger and the cathode, so no arc can take place. Once it is noticed that MeVVA has stopped firing, we take off the MeVVA assembly as instructed here. We then, sand down the insulator to remove the plating. The MeVVA is replaced and we are allowed to run again. After repeating this process about 4-5 times, the the cathode material becomes eroded. At this point it becomes necessary to grind the cathode down to expose fresh sample material. This is very tedious and slows the data taking process down considerably. New designs have been suggested and are currently being fabricated. These designs are illustrated here.