A behavior of arc under an obliquely irnposed alternating magnetic field to the arc is theoretica 旦 ly investigated . It is known that the arc oscillates in a plane when the alternating magnetic field is imposed perpendicularly to the arc . hl the present work , the governing equation f -) r arc motion is obtained and solved . The numerical analysis results suggest that motion of the oscillating arc with obliquely imposed altemating magnetic field becomes three − dhnensional pattem and there is

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... a possibility for the arc to be unstable under some conditions . When the crossing angle f( )r imposed alternating magnetic field to the arc larger than πノ 4 [ rad 】 , the trqjectory ofthe plasma gas 丘action is upturned . On the contrary , the crossing angle smaller than π14 [ rad 】 , the trajeCtory Gf the plasma gas fraction is always downward and the arc has a root on the anode . Variations of the arc motion dqpend on the erossing angle f()r imposed alternating magrietic field to the arc .