| AVS 60th International Symposium and Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS+AS+BI+SE-MoM |
| Session: | Atmospheric Plasma Processing: Fundamental and Applications |
| Presenter: | J-C. Wang, University of Michigan |
| Authors: | J-C. Wang, University of Michigan Z. Xiong, University of Michigan C. Eun, University of Michigan X. Luo, University of Michigan Y. Gianchandani, University of Michigan M.J. Kushner, University of Michigan |
| Correspondent: | Click to Email |
Pressure monitors in hostile environments often use piezoresistive and capacitive based sensors. The smallest dimension of this class of sensors is about 1 mm. Recently, a microplasma-based pressure sensor has been developed which is capable of dimensions at least an order of magnitude smaller. In these sensors, a plasma is initiated between an anode and two competing cathodes in a sealed chamber having a diaphragm as one surface. External pressure deflects the diaphragm which changes the inter-electrode spacing for one of the anode-cathode pairs, thereby redistributing the current collected by the two competing cathodes. Pressure is then proportional to the relative difference in current collected by the two cathodes.
In this presentation, we will discuss the properties of microplasma-based pressure sensors using results from a two-dimensional simulation. The model, nonPDPSIM, solves Poisson’s equation, transport equations for charged and neutral species, and the electron energy conservation equation for electron temperature. Radiation transport is addressed using a Green’s function approach, and sheath accelerated electrons are addressed using Monte Carlo methods. The microplasma is sustained between an anode (A) biased with hundreds of volts and two grounded cathodes (K1, K2) in a sealed chamber filled with 1 atm of Ar or rare gas mixtures. The reference cathode (K1) is located adjacent to the anode while the sensing cathode (K2) is mounted on the diaphragm separated by a gap of 10 to 100 µm. We find that following a small amount of electric field emission of electrons from the edges of K1 and K2, the electrons rapidly avalanche in the geometrically enhanced electric field at the edge of the anode and creates a conductive plasma within tens of ns. The current distribution on K1 and K2 varies with inter-electrode spacing (AK2) which is changed by deflection of the diaphragm due to the external pressure. The current distribution can also be optimized by adjusting the impedance connected to electrodes.
*Work was supported by the Advanced Energy Consortium.