line ▁will ▁experience ▁a ▁force ▁out wards , ▁causing ▁a ▁growing ▁bul ge ▁that ▁will ▁eventually ▁reach ▁the ▁re actor ▁wall . ▁ ▁These ▁inst abilities ▁have ▁a ▁natural ▁pattern ▁based ▁on ▁the ▁rot ational ▁transform . ▁This ▁leads ▁to ▁a ▁characteristic ▁w avel ength ▁of ▁the ▁k inks , ▁which ▁is ▁based ▁on ▁the ▁ratio ▁of ▁the ▁two ▁magnetic ▁fields ▁that ▁mix ▁to ▁form ▁the ▁tw isted ▁field ▁in ▁the ▁pl asma . ▁If ▁that ▁w avel ength ▁is ▁longer ▁than ▁the ▁long ▁radius ▁of ▁the ▁re actor , ▁then ▁they ▁cannot ▁form . ▁That ▁is , ▁if ▁the ▁length ▁along ▁the ▁major ▁radius ▁ ▁is : ▁ ▁Then ▁the ▁pl asma ▁would ▁be ▁stable ▁to ▁this ▁major ▁class ▁of ▁inst abilities . ▁Basic ▁mathematical ▁re arr ang ement , ▁removing ▁the ▁ ▁from ▁both ▁sides ▁and ▁moving ▁the ▁major ▁radius ▁R ▁to ▁the ▁other ▁side ▁of ▁the ▁equality ▁produces : ▁ ▁Which ▁produces ▁the ▁simple ▁rule ▁of ▁thumb ▁that ▁as ▁long ▁as ▁the ▁safety ▁factor ▁is ▁greater ▁than ▁one ▁at ▁all ▁points ▁in ▁the ▁pl asma , ▁it ▁will ▁be ▁naturally ▁stable ▁to ▁this ▁major ▁class ▁of ▁inst abilities . ▁This ▁principle ▁led ▁Soviet ▁research ers ▁to ▁run ▁their ▁tor oid al ▁pin ch ▁machines ▁with ▁reduced ▁current , ▁leading ▁to ▁the ▁stabil ization ▁that ▁provided ▁much ▁higher ▁performance ▁in ▁their ▁T - 3 ▁machine ▁in ▁the ▁late ▁ 1 9 6 0 s . ▁In ▁more ▁modern ▁machines , ▁the ▁pl asma ▁is ▁pressed ▁to ▁the ▁outside ▁section ▁of ▁the