Since runaway electrons and magnetohydrodynamics activity can contribute to serious damage and energy losses in tokamaks, the effect of an external electric field on runaway electrons and hard x-ray spectra is investigated. Parameters such as the plasma current, the hard x-ray photons count and the mean energy of runaway electrons are measured. Positive and negative voltages of 300 V are applied at 10 ms after the plasma initiation (while the plasma is forming), at 15 ms (while the plasma is stable) and at 20 ms (while the plasma is fading away) to attain the most effective time of applying the external electric field. The number of hard x-ray photons has the most changes in the range of 0–200 keV when the external electric fields are applied. Also in the duration of 20–30 ms of plasma the greatest number of hard x-ray spectra is detected. When the external electric fields are applied, the mean energy of runaway electrons reduces significantly, especially at 15 ms (while the plasma is stable).

Keeping the plasma stable throughout the plasma discharge is now considered a massive undertaking in today’s Tokamaks. In this study, the part that the current rise up phase plays in the total plasma stability was investigated, toroidal magnetic field on IR-T1 Tokamak was altered to reach the least amount of instabilities in current rise up phase. In this experiment, in order to provide rigorous and details affirmation, SVD, FFT and hard X-ray analyses were employed. The results state that with toroidal magnetic field increment to a specific amount (3.10 KV), the plasma experiences the least amount of Mirnov oscillations (almost 25%) and instabilities during current rise up phase.