Oneofthemostfascinatingignitionschemesfortheinertialfusionenergythatmightbefeasibleisfastignition.Itstargetsareignitedontheoutsidesurfacesothereisnoneedtolowdensityandhightemperaturecenterisrequiredbycentralhotspotignition.Fastignitionconceptisnoteworthyforasimplebutfundamentalreason:Inprincipleitrequireslesstotalenergyinputtoachieveignition.Inthispaper,fuelenergyandfuelenergygainofnearlypuredeuteriumcapsulearecalculated.Thiscapsuleisignitedbyadeuterium-tritiumseed,whichwouldreducethetritiuminventorytoafewpercentages.Thevariationsoffuelenergygainversusfueldensityhavebeenstudiedandsubmitted.Onthebasisofdifferentphysicalparametersthefollowingresultsoftheinvestigationarepresentedanddiscussed.Theenergygaincurvesfordifferenttritiumconcentrationsarefoundandlimitinggaincurvesarederived.Finally,tritium-poorfastignitoriscomparedtoequimolardeuterium-tritiumfastignitor.
