简介：Anew140GHz/2MW/3selectroncyclotronresonanceheating(ECRH)systemcomposedoftwounitsisnowbeingconstructedonHL-2A.Asapartofthesystem,twotransmissionlinesmarkedNo.7&8playtheroleofcarryingmicrowavepowerfromtwogyrotronstothetokamakport.Basedontheoversizedcircularcorrugatedwaveguidetechnology,anevacuatedtransmissionsystemwithhighpowercapabilityandhightransmissionefficiencyisdesigned.Detailsarepresentedforthedesignofthecorrugatedwaveguide,thelayoutoftheproposedlinesandthevacuumpumpingsystem.Thenmodeconversionlossesduetocoupling,misalignment,bendsandgapsarediscussedtoserveasareferenceforanalyzingthetransmissionefficiencyandalignment.Finally,adual-modespropagationcaseconsistingoftheHEnandLPnevenmodesisdiscussed