Miniaturized double transit magnetic field measurement probe using the Faraday rotation principle.

This paper presents the design and experimental results of a double transit magnetic field measurement probe based on the Faraday rotation principle using terbium doped borosilicate glass as a sensor element. When the magnetic field is applied in the direction of propagation of light through the glass, the Faraday effect produces non-reciprocal circular birefringence. This property of the Faraday effect adds rotations when the light beam is reflected using a mirror placed at the other end of the glass and passed through the glass, making double transit of light through the sensor element. Experiments were carried out to verify the characteristics of the designed probe by inserting it inside the solenoid load coil. The Verdet constant of the glass is determined using the slope of the linear least-squares fitted curve between the Faraday rotation angle and the applied magnetic field, obtained as 89.22r a d/(T⋅m) with a relative uncertainty of 2.43%. The magnetic field was measured with 0.28% accuracy. In the optics experiments, alignment of components is the major task. To the authors' knowledge, this is the first of its kind double transit miniaturized magnetic field measurement probe configuration in which components are aligned inside the single probe structure. The probe is easily portable and can be used in inaccessible locations in various applications such as accelerators, Z/θ pinch devices, or fusion reactors such as tokamaks, in which the magnetic field is one of the main parameters.

Plasma triggered spark gap switch for multiple switch synchronization.

A four-electrode plasma based triggered spark gap switch is designed for pulsed power applications, which consists of an anode and cathode of a main spark gap switch and an anode and cathode for a trigger pin. The anode and cathode of the trigger pin are coaxially arranged, and the gap between electrodes is 25 µm. A trigger voltage of 200 V is applied across the trigger gap with the help of a switching insulated gate bipolar transistor. With the breakdown of the trigger gap, plasma is generated, which is injected into the main gap. The trigger pin is placed axisymmetric to the main spark gap in the cathode. The main discharge channel of the spark gap has 0.6 mm space between two electrodes, which is charged to 1000 V. When the spark gap is triggered, the discharge current has a peak value of 6.1 kA with a quarter cycle time period of 0.97 µs. The four-electrode spark gap switch results are compared with those of a three-electrode trigatron switch, which has the peak current of 6 kA with 1.01 µs as quarter-cycle time period. Four similar four-electrode spark gap switches are triggered with the same scheme and synchronized within 10 ns as peak values of currents with jitter as less than 5 ns.