An Experimental Investigation on Cavity Pulsed Heating

Cav­i­ty pulsed heat­ing ex­per­i­ments have been con­duct­ed at SLAC Na­tion­al Ac­cel­er­a­tor Lab­o­ra­to­ry in col­lab­o­ra­tion with CERN and KEK. These ex­per­i­ments were de­signed to gain a bet­ter un­der­stand­ing on the im­pact of high power pulsed mag­net­ic fields on cop­per and cop­per al­loys. The cav­i­ty is a one port hemi­spher­i­cal cav­i­ty that op­er­ates in the TE013-like mode at 11.424 GHz. The test sam­ples are mount­ed onto the end­cap of the cav­i­ty. By using the TE013 mode, pulsed heat­ing in­for­ma­tion can be an­a­lyzed that is based only on the im­pact of the peak mag­net­ic field which is much big­ger in value on the test sam­ple than on any other place in the cav­i­ty. This work has shown that pulsed heat­ing sur­face dam­age on cop­per and cop­per al­loys is de­pen­dent on pro­cess­ing time, pulsed heat­ing tem­per­a­ture, ma­te­ri­al hard­ness, and crys­tal­lo­graph­ic ori­en­ta­tion and that ini­tial stress­es occur along grain bound­aries which can be fol­lowed by pit­ting or by trans­gran­u­lar mi­crofrac­tures that prop­a­gate and ter­mi­nate on grain bound­aries. The level of pulsed heat­ing sur­face dam­age was found to be less on the small­er grain sam­ples. This is like­ly due to grain bound­aries lim­it­ing the prop­a­ga­tion of fa­tigue cracks.