In this paper, nitrogen dielectric barrier discharge (DBD) plasma was generated in a quartz tube with coaxial wire-cylinder electrodes at atmospheric pressure. By varying the nitrogen gas flow (FN) in the range of 0-1 m 3 /h, the plasma optical emission spectra (OES) were measured and studied. The vibration (T vib) and rotation temperature (Trot) of nitrogen were obtained, by fitting the rovibronic bands of N2(C 3 Πu − B 3 Πg, 0-1), and by the Boltzmann plot method for purposes of comparison. T vib increased up to 2481 K with increasing nitrogen flow till 0.2 m 3 /h, and then decreased with further increasing FN , while Trot decreased monotonously and approached to ∼350 K for FN ≥ 0.6 m 3 /h. The intensity of N2(C 3 Πu − B 3 Πg, 0-0, 1-0, 0-3) and N + 2 (B 2 Σ + u − X 2 Σ + g , 0-0) exhibited similar evolution with increasing FN to those of the T vib and Trot, respectively. The discharge photos revealed that the discharge filaments gradually decreased with increasing FN , and eventually disappeared, which implied that a discharge mode transition emerged with increasing FN. The possible mechanism for the discharge mode transition is studied in detail according to the vibration (T vib) and rotation temperature (Trot) of nitrogen.

High-power pulsed magnetron sputtering (HPPMS or HiPIMS) is an emerging coating technology that produces very dense plasmas and highly ionized sputtering atoms. This paper is focused on discharge properties, unbalanced features and temporal evolution of pulse current of the HPPMS discharge. A hollow cathode was used to suppress the scattering of charges. A coaxial coil surrounding the target was used to control the breakdown voltage and pulse repetition frequency by varying the coil current. A Langmuir probe and an oscilloscope were used to simultaneously measure the floating potential, pulse voltage and pulse current signals. The pulse power density in the discharge reached 10 kW/cm 2 with frequencies as high as ∼40 Hz and a pulse width about 1∼5 ms. The characteristics of the discharge evolution were analyzed using magnetron discharge dynamics.

In this paper a numerical simulation of a planar DC magnetron discharge is performed with the Particle-in-Cell/Monte Carlo Collision (PIC/MCC) method. The magnetic field used in the simulation is calculated with finite element method according to experimental configuration. The simulation is carried out under the condition of gas pressure of 0.665 Pa and voltage magnitude of 400V. Typical results such as the potential distribution, charged particle densities, the discharge current density and ion flux onto the target are calculated. The erosion profile from the simulation is compared with the experimental data. The maximum erosion position corresponds to the place where the magnetic field lines are parallel to the target surface.

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High Power impulse Unbalanced Magnetron Sputtering has been coupled to a direct current source (dc-HPPUMS or dc-HiPUMS). A coaxial coil and an attached hollow cathode were applied to control discharge properties and improve pulsed power density. A large extent breakdown was induced for avalanche discharge mechanism. The magnetic trap on sputtering target traps the secondary electrons excited by the avalanche and forms a drift current in magnetic trap. The peak pulse current density is higher than 100 A/cm2 with a pulse frequency less than 40 Hz. The space charge limited condition controls the discharge for plasma far away from equilibrium. The discharge theory was taken to describe the high ionization mechanism in dc-HPPUMS discharge. The parameters deduced from Child law agree with the experimental results.