The aim of this paper is to compare the electrical performance of an orthogonally with a coaxially laser-triggered spark
gap. Each of these two gaps has its own advantages and disadvantages. At the same time, a Rogowski profile spark gap
was investigated in terms of its orthogonally laser-triggered performance. It was found that the Nd:YAG laser used
(1 064 nm, 800 mJ) was able to reduced the breakdown voltage of a 50 mm gap by 70% from 135 kV to about 40 kV.
The position of the laser-induced plasma was found to play a significant role in the breakdown process - best results
being obtained when the laser was focused in the centre of the gap. Finally, the shape of the laser-induced arc is
dependant on the applied electric field. When the field is low, the arc tends to avoid the laser-induced plasma thus
exhibiting a very anomalous behaviour. When the field is increased, the arc tends to attach itself to the plasma as