Introduction  By adding parallel electron viscosity into the normal equation of resistance tearing mode, the nonlinear behavior of double tearing mode (DTM) mediated by parallel electron viscosity is numerically investigated considering the magnetohydrodynamics in a periodic cylinder.

  Method  The evolution of magnetic islands and magnetic flux during the nonlinear behavior stage of double tearing mode mediated by parallel electron viscosity were analyzed, to study the changes of the magnetic field topology in different phases and associated kinetic characteristics for different distances between the two resonant rational flux surfaces. In addition, the nonlinear driving for each case was discussed.

  Result  The results show that the distance between the two resonant rational flux surfaces has a significant impact on the nonlinear behavior of double tearing mode. Rapid magnetic reconnection would occur at an intermediate distance, resulting in the fastest and most severe damage to the configuration.

  Conclusion  The results of this study provide a reference for the configuration design and operational control of tokamaks.