Packed bed dielectric barrier discharges (DBDs) are very promising for several applications including remediation of environmental pollutants and greenhouse gas conversion. In this work, we have investigated the space and time-resolved emission from a packed bed DBD operated in helium, to understand the plasma dynamics. We have chosen a simple planar DBD arrangement with a patterned dielectric, which mimics the spherical boundaries between the dielectric pellets and allows the optical access to the plasma. The results show that plasma is sustained in a packed bed DBD by three mechanisms: filamentary discharge in the void (between the center of dielectric structures and the opposite electrode), microdischarges at the contact points and surface ionization waves over the dielectric surface. It is observed that for most of the duration plasma is generated at the contact points between the dielectric structures.

The concentration of two species in a multi-dipole plasma was determined by measuring the ion acoustic wave group velocity and the electron temperature. The wave was launched from a grid immersed in the plasma and was detected by a Langmuir probe. Electron temperature was found separately from an $\mathrm{I–V}$ characteristic trace. The measurements were performed in helium/xenon and argon/xenon plasmas. Typical parameters of the plasma were $T_e\text{∼0.5–3\hspace{0.05em}}\mathrm{eV},$ density ${10}^{10} {\mathrm{cm}}^{\text{−3}},$ plasma potential of 3–5 V, and pressure range from 1 to 20 mTorr. The accuracy of the measurement was from 2% to 4% depending on the mass difference between the two species and how accurately the group velocity and electron temperature are measured.

A waveguide-based microwave plasma system was built using a resonant cavity and a quartz tube. 2.45 GHz 850 W magnetron was used to obtain helium discharge without an igniter. The temporal images of discharge were recorded on microsecond time scales using an intensified charge-coupled device camera. The excitation temperature was calculated as 3385 K using the helium lines, which were obtained from emission spectrum of the discharge. The gas temperature was measured as 1208 K by a thermocouple.

A new type of hybrid discharge is experimentally investigated in this work. A helicon source and an electron cyclotron resonance (ECR) source were combined to produce plasma. As a preliminary study of this type of plasma, the optical emission spectroscopy (OES) method was used to obtain values of electron temperature and density under a series of typical conditions. Generally, it was observed that the electron temperature decreases and the electron density increases as the pressure increased. When increasing the applied power at a certain pressure, the average electron density at certain positions in the discharge does not increase significantly possibly due to the high degree of neutral depletion. Electron temperature increased with power in the hybrid mode. Possible mechanisms of these preliminary observations are discussed.

This paper presents a comprehensive investigation into the deterministic chaotic behavior of a quiescent physical plasma system, bridging empirical observation with a new theoretical framework. We first revisit an experimental analysis of Langmuir probe current-voltage (I-V) traces, where a quadratic fit of the electron saturation region revealed a discrete recurrence relation. The resulting bifurcation diagram unequivocally demonstrates a period-doubling cascade leading to a chaotic regime, providing strong empirical evidence for nonlinear dynamics inherent in the plasma-probe interaction. To model this observed behavior, we introduce the Hala attractor, a low-dimensional dynamical system inspired by the Lorenz equations but modified with a self-regulating feedback mechanism. We demonstrate the Hala attractor’s ability to model two key phenomena: a spatial transition from chaos at the magnetically confined plasma boundaries to a stable state in the quiescent bulk, and a temporal transition to chaos induced by the active perturbation of a diagnostic probe. The model’s simulation results, including a bifurcation from a stable fixed point to a chaotic attractor and the emergence of hysteresis in simulated I-V curves, quantitatively validate the Langmuir probe's experimental findings. By unifying these empirical and theoretical approaches, we establish that chaos in this system is not a fixed, intrinsic property but a dynamic, tunable state dependent on both spatial location and the influence of external measurement. This work provides a powerful, unified framework for interpreting experimental data and reinforces the value of applying chaos theory to understand complex plasma phenomena.