The influence of AC axial magnetic (AM) fields on the development of half-cycle drawn vacuum area is described. A Helmholtz coil provided an independent AC AM field B/sub ax//sup ac/ in the opening gap between flat profile, butt type, Cr-Cu contacts. For peak arc currents I/sub p/ up to 20 kA, critical fields B/sub crit//sup ac/ were determined which prevented anode involvement. The dependence of B/sub crit//sup ac/ on I/sub p/ is compared with the analogous dependence using constant magnetic fields B/sub ax//sup dc/. The results are used to extend the usefulness of the B/sub crit/ parameter to the design of contact structures which produce self-generated axial magnetic fields from the AC arcing current. A similar direct transition to the diffuse arc mode occurs without an imposed B/sub ax/ for separation currents I/sub s/>7 kA and I/sub p/>10 kA.
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机译：描述了交流轴向磁场（AM）对半周期抽真空区域发展的影响。亥姆霍兹线圈在扁平轮廓，对接型Cr-Cu触点之间的开口间隙中提供了一个独立的AC AM磁场B / sub ax // sup ac /。对于最大20 kA的峰值电弧电流I / sub p /，确定了防止阳极参与的临界场B / sub crit // sup ac /。将B / sub crit // sup ac /对I / sub p /的依赖性与使用恒定磁场B / sub ax // sup dc /的类似依赖性进行比较。结果用于将B / sub crit /参数的有用性扩展到接触结构的设计，该结构从交流电弧电流产生自生的轴向磁场。对于隔离电流I / sub s /> 7 kA和I / sub p /> 10 kA，在没有施加B / sub ax /的情况下，发生了类似的直接过渡到扩散电弧模式的操作。
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