For laboratory and technical plasmas, the electrodes are most commonly tungsten or tantalum wires several thousandths of an inch thick, because they have a high melting point but can be made small enough not to perturb the plasma. Although the melting point is somewhat lower, molybdenum is sometimes used because it is easier to machine and solder than tungsten. For fusion plasmas, graphite electrodes with dimensions from 1 to 10 mm are usually used because they can withstand the highest power loads (also sublimating at high temperatures rather than melting), and result in reduced bremsstrahlung radiation (with respect to metals) due to the low atomic number of carbon. The electrode surface exposed to the plasma must be defined, e.g. by insulating all but the tip of a wire electrode. If there can be significant deposition of conducting materials (metals or graphite), then the insulator should be separated from the electrode by a to prevent short-circuiting.
FOr LaBORatoRy and tEchnical pLasMAS, the elEctroDes are most cOmmONly TUngsteN or taNtAluM wiRes seVERAl ThoUsandtHs OF An Inch thick, beCause they HAve A High melTing pOiNt but can be madE sMalL enoUGH NOt To pERturb thE pLAsmA. AlthoUgh The MeltiNg pOint is SOmewhat loweR, molybdeNum is SometimeS uSed BecaUSE it is eAsiEr tO maCHinE and solder tHAN tunGsten. FOr fuSIon PlaSmAs, gRaphite eleCtRodes wiTh DIMEnsIoNs from 1 to 10 mm aRe Usually useD beCause thEY Can wiThstaND THe hiGHeST poWEr LOaDs (alsO SuBLIMaTiNG aT high tEMpERatures rATHEr thaN meLtINg), ANd Result in reDucEd bremsSTraHluNg radiation (WIth respEct to meTAlS) due tO ThE loW atomic NUMber of cARBon. the elEctrodE sUrFaCe eXPosEd To tHe plaSma must be deFined, e.g. bY InsulatiNg aLl but tHe tiP oF a Wire eleCtroDe. If theRe can bE SIGnIfIcAnt DepositioN Of conduCTINg maTErIaLS (meTALs Or grApHiTe), ThEn the iNsulator SHoULd bE sepaRatED frOM the eLectrodE by a To prEVEnt short-ciRcuiTing.