Highvoltage Discharge Experiment 31 Experimental model

An experimental apparatus incorporating multiple reflection optics was constructed to verify whether the polarization plane rotation of a propagating beam due to an electrical discharge can be detected. The experimental setup is shown in Fig. 2, and the specifications are shown in Table 1. The propagating beam runs repeatedly around the discharge path so that the beam can interact with the high-voltage discharge multiple times, providing enough rotation in the polarization plane due to the Faraday effect. The optics consists of input-output optics and a square mirror. The latter is installed inside a discharge chamber.

The discharge gap consisting of two needle electrodes is at the center of the square mirror. The polarization and divergence of the beam are adjusted on entering the square mirror. The total length of the optical path can be changed by controlling the tilts of the four sides of the square mirror.

The outgoing beam from the square mirror is divided by a polarized beam splitter and detected separately at mutually orthogonal polarizations. The polarization of the incident beam is adjusted to balance the detected intensities. An impulse voltage is applied to the needle electrode, causing a spark discharge inside the chamber. This causes a rotation in the polarization plane of the propagating beam, and the difference between the intensities of the two mutually orthogonal polarizations is detected by a differential amplifier.

Top View Discharge Chamber

Fig. 2. High-voltage discharge experiment.

Table 1. Specification of high-voltage discharge experiment.

Detection PDs with Amp. + Differential Amplifier Discharge gap 3—10 cm Discharge voltage 180 kV (max) Beam path length 19—50 m (max)

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