Studies of Transient Photoplasma Evolution in an Electrostatic Field: Single Particle Motion to Its Collective Behavior

Though the plasma is an ensemble of charged particles, its behavior in an electrostatic field is different from that of individual particles. It shows a collective behavior as a result of long-range Coulomb interactions among the charged particles. To elucidate the plasma behavior, the transient evolution of photoplasma in an applied electrostatic field is carried out in two different density regimes where the plasma shows its single particle motion and collective behavior. In the case of low-density plasma, the external electric field dominates the plasma motion. The electrons and ions act as two independent entities and the plasma shows its single particle behavior in the external field, whereas in the high-density plasma regime, the self-generated electric field in the plasma is comparable to the applied external field. The plasma motion is governed by both the internal ambipolar electric field in the plasma as well as the applied electrostatic field. Thus, the plasma shows its collective motion due to Coulomb interactions among the charged particles.