INSTABILITY OF VACUUM-ARC IN AG-CU CONTACT ALLOYS

To clarify the effect of material characteristics of contact on the ar c instability and chopping phenomena, we measured the spectrum intensi ty of ionized and neutral vapor generated during discharge continuousl y using contacts of Ag-Cu binary alloys. We observed that arc instabil ity and chopping phenomena are closely related to the behavior of ioni zed vapor during discharge and we found that the chopping current decr eases with increased content of Ag, while the instability starting cur rent indicates the minimum value at 60 at % of Ag content. We will dis cuss such effects of material composition on arc instability and chopp ing phenomena from the viewpoint of the ion generation ability includi ng thermal properties of contact materials.