A thermally insulating panel (e.g., vacuum IG window unit) includes first and second opposing substrates spaced apart from one another by a plurality of spacers. A low pressure space is defined between the substrates, and is hermetically sealed off by at least one edge seal. During evacuation of the space, a plasma is ignited within the space via a static grid assembly in order to reduce the time needed to evacuate the space down and/or to help remove debris from within the space to the desired low pressure.