▁w eld ing ▁has ▁spread ▁rapidly ▁in ▁all ▁branches ▁of ▁engineering ▁where ▁w eld ing ▁can ▁be ▁applied . ▁To ▁cover ▁the ▁various ▁requirements , ▁count less ▁wel der ▁types ▁have ▁been ▁designed , ▁differ ing ▁in ▁construction , ▁working ▁space ▁volume , ▁work pie ce ▁manip ul ators ▁and ▁beam ▁power . ▁Electron - be am ▁gener ators ▁( elect ron ▁guns ) ▁designed ▁for ▁w eld ing ▁applications ▁can ▁supply ▁be ams ▁with ▁power ▁r anging ▁from ▁a ▁few ▁w att s ▁up ▁to ▁about ▁one ▁hundred ▁kil ow att s . ▁" M icro - w eld s " ▁of ▁tiny ▁components ▁can ▁be ▁realized , ▁as ▁well ▁as ▁deep ▁w eld s ▁up ▁to ▁ 3 0 0   mm ▁( or ▁even ▁more ▁if ▁needed ). ▁V acu um ▁working ▁ch amb ers ▁of ▁various ▁design ▁may ▁have ▁a ▁volume ▁of ▁only ▁a ▁few ▁lit ers , ▁but ▁vac u um ▁ch amb ers ▁with ▁the ▁volume ▁of ▁several ▁hundreds ▁cub ic ▁meters ▁have ▁also ▁been ▁built . ▁ ▁Specifically , ▁the ▁equipment ▁compr ises : ▁▁ ▁Electron ▁gun , ▁generating ▁the ▁electron ▁beam , ▁ ▁Working ▁chamber , ▁mostly ▁ev acu ated ▁to ▁" low " ▁or ▁" high " ▁vac u um , ▁ ▁Work pie ce ▁manip ulator ▁( position ing ▁mechanism ), ▁ ▁Power ▁supply ▁and ▁control ▁and ▁monitoring ▁electron ics . ▁ ▁Electron ▁gun ▁ ▁In ▁the ▁electron ▁gun , ▁the ▁free ▁electrons ▁are ▁gained ▁by ▁therm o - em ission ▁from ▁a