Harmonic hexagonal superlattice pattern in a dielectric barrier discharge at atmospheric pressure

We report a harmonic hexagonal superlattice pattern in a dielectric barrier discharge in air/argon mixture at atmospheric pressure. The bifurcation scenario of harmonic hexagonal superlattice pattern with the applied voltage increasing is given. The phase diagram of the pattern types as a function of the applied voltage and the air-concentration is obtained. The hysteresis of pattern transitions at the upward and downward stage of the applied voltage is observed. The correlation measurements indicate that harmonic hexagonal superlattice pattern is an interleaving of two different transient sublattices. The spatial power spectrum demonstrates that harmonic hexagonal superlattice pattern has two separate wave vectors. Both small wave vector q _h and big wave vector K _h belong to the harmonic mode, and they obey a triad resonant interaction q _h ¹ + q _h ² =k _h . Supported by the National Natural Science Foundation of China (Grant Nos. 10775037, 10575027), Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050075001) and Natural Science Foundation of Hebei Province (Grant No. A2008000564)