and proximal to the distal end of core member 20 in the embodiment illustrated in fig1 5 the electrodes 16 are helical coils which are electrically connected to insulated electrical conductors 29 the temperature sensors 17 are thermocouples formed by thermocouple wires 30 and 31 as best illustrated in fig4 and 5 showing transverse cross sections of the device shown in fig3 taken along lines 4 u2014 4 and 5 u2014 5 the braided electrical conductors 29 are formed of 36 awg copper wire with each conductor having a polyimide insulating coating of about 0 0005 inch thick 0 013 mm the thermocouple wires are formed of 41 awg copper and constantan with each wire having a polyimide insulating coating of about 0 00025 inch 0 007 mm to about 0 0005 inch 0 013 mm thick the shaft 11 comprises a braided structure formed by the electrical conductors 29 and the thermocouple wires at least partially coated with a jacket 32 in a presently preferred embodiment the jacket 32 is a fluoropolymer such as thv in the presently preferred embodiment illustrated in fig1 braided electrical conductors 29 and the thermocouple wires 30 31 are also at least partially within the coating 28 around the core member 20 a conducting member 33 covers the outer surface of the temperature sensors 17 the conducting member 33 is preferably a gold band of.