|Plasma Research Laboratory
Plasma research laboratory is engaged in conducting experimental investigation in low pressure (10 mTorr-1 Torr) radio-frequency driven discharge plasmas and develop a knowledge base enabling the use of these plasmas in various areas of Space Enterprise such as, but not limited to: (i) Semiconductor material processing, (ii) Mars sample sterilization processes, and (iii) Production of nano tubes. The data so acquired will be used to validate CFD and process models under construction, bench mark the rate and cross section data produced by computational analysis, experimentally verify the measured and computed chemical data by studying the individual processes in an experimental reactor, such as GEC cell, and provide the necessary link between the gas phase chemistry and process effectiveness. In order to provide a systematic and effective approach to the problem, the investigation process needs to be divided into three steps:
||Investigation of individual processes in a controlled laboratory environment. This task is devoted to the basic understanding of the chemical kinetics involved in a given discharge mixture. Representative composition of mixtures used in the industry for process is selected for this purpose. The investigation is concentrated on determining the chemical composition of the plasma along with the measurements of bulk plasma parameters, such as plasma impedance, input power and current density, describing the discharge.
||Measurements of individual cross-sections. In order to be able to identify the role of individual reactions in a given process precise knowledge of individual cross-section is important. The database on needed cross-sections is, at best, sketchy, incomplete, and some times unreliable. In an attempt to (1) fill-in the gaps in needed data, (2) validate and verify the accuracy of questionable data, and (3) provide a validation mechanism for theoretical/computational data, efforts are being made to acquire cross-sectional data for certain individual molecules. At this initial stage only electron-impact cross-sections are measured.
||Interpretation of the findings. This is the most important aspect of the investigation. By entertaining a serious dialog with the in-house reactor modeling group and with the help of a thorough data analysis interpretation of the experimental findings will help us in our understanding of the basic physical processes of these plasmas.
There are two experimental setups in the plasma research laboratory:
The GEC cell, primarily designed to study inductively coupled plasmas, is currently equipped with various diagnostics - (1) Mass Spectrometer, (2) Langmuir Probe, (3) Fourier Transform Infrared (FTIR) spectroscopy, (4) Ultraviolet (UV) absorption, (5) Optical Emission Spectroscopy (OES), and (6) Plasma Impedance Monitoring (PIM). Two additional diagnostics, namely, (i) microwave spectroscopy and (ii) diode laser based cavity ringdown absorption spectroscopy are under construction. The cell is used to investigate the physical processes occurring in the plasma for a given mixture under predetermined operating conditions.
Crossed Beam Experiments:
In this experiment a beam of test molecules is bombarded by an electron beam of known strength and the interaction products are detected by a quadrupole mass spectrometer to deduce the cross sectional data. This setup is designed to measure partial and total cross sections of electron impact ionization, dissociation, and dissociative attachment processes occurring in polyatomic molecules.
Dr. Sharma is the lead scientist of the laboratory and is, working with other researchers of the laboratory, engaged in conducting research in the above-mentioned areas.