Best impedance matching seeking of single-frequency capacitively coupled plasmas by numerical simulations

Abstract

Impedance matching can maximize the absorbed power transferred to the plasma load and minimize the reflected power, making it critical and indispensable for capacitively coupled plasmas (CCPs). The external circuit usually interacts with the plasma nonlinearly, so the global simulation of the external circuit and plasma and the matching design is very challenging. In this work, an a priori model was proposed to match the plasma impedance and the external circuit impedance for single-frequency CCPs. By calculating the plasma impedance and the matching network, the matching parameters were iteratively updated to find the best matching parameters. By adjusting the capacitance and the inductance of the circuit by numerical simulations, the reflection coefficient can be significantly reduced. At the same time, the plasma power absorption efficiency will be significantly improved. The universality of the method was demonstrated by choosing different initial circuit, discharge, and plasma parameters. The proposed method provides an effective matching design reference for CCPs.

Numerical impedance matching via extremum seeking control of single-frequency capacitively coupled plasmas

“…In addition, in the process of CCP impedance matching seeking, the initial point often deviates from the desired point, and the system state is far from the requirement of impedance matching in a considerable range. The range of matching parameters suitable for CCP is very narrow [6]. Therefore, the step size cannot be determined according to the gradient value.…”

“…The larger the voltage amplitude, the stronger the discharge. The second objective function is the reflection coefficient Γ = (Z L − Z s )/(Z L + Z s ), where Z s and Z L are the source impedance and the equivalent input impedance on the right side of point B (Γ is obtained by the Fourier transform, reference [6,14]), respectively. This objective function can constrain the reflected power to increase the power delivered to the load.…”

“…Eight simulations are conducted to confirm the extremum seeking process with U ccp and Γ as optimization objectives. The appropriate initial matching parameters are selected by roughly scanning the parameter space of IMN or using an a priori model [6]. According to experience from this priori model, the optimization is considered convergent when the U ccp change or Γ was less than the specified value.…”

“…Many investigations on impedance matching have been reported, including numerical simulations [4] and experiments [5]. In computational investigations of capacitively coupled plasmas [6] and inductively coupled plasmas (ICPs) [7], the load impedance can be obtained from numerical diagnostic data (voltage, current, et al). The IMN parameters corresponding to the current load impedance can then be calculated using circuit theory.…”

Influence of pulse width on the breakdown process of nanosecond pulse discharge at low pressure

“…If it is too large, the plasma cannot be broken down; if it is too small, the current-limit effect cannot be achieved. The resistance model has been successfully used for breakdown simulation [47,48]. In this work, after many simulations, the external resistance is set to 200 Ω, and the partial voltage of the resistance is reasonable.…”