1. Measurements of several parameters of plasma panels October 2011

2. Parameters of interest Effective capacitance in panel – Gas gap – Electrode width

3. Motivation

4. Methods Capacitance measurement – Used standard capacitance meter – Split each panel into 9 approximately equal areas Effective capacitance could be a function of position on panel – Took many measurements across electrodes in each area Gas gap measurement – Used standard calipers to measure plate and panel thicknesses

5. Sample gas gap calculation and uncertainty MeasurementPlate 1 (mm)Plate 2 (mm)Whole panel (mm) 13.103.086.48 23.123.076.50 33.083.126.60 43.103.056.63 53.083.076.63 Average3.10 ±.04473.08 ±.04476.57 ±.0447

6. Large Vishay All values in pF, with uncertainty ± 1 pF Gas gap: 0.38 ±.08 mm Electrode width: 1.23 ±.01 mm 555 665 665

7. Large Babcock All values in pF, with uncertainty ± 1 pF Gas gap: 0.39 ±.08 mm Electrode width: 1.22 ±.01 mm 888 887 877 Coming soon

8. VF - mini All values in pF, with uncertainty ± 1 pF Gas gap: 0.29 ±.08 mm Electrode width: 0.88 ±.01 mm 444 444 555

9. Xe filled panel All values in pF, with uncertainty ± 1 pF Gas gap: 0.16 ±.08 mm Electrode width: 0.34 ±.01 mm 211 221 322

10. Big Panel 1 All values in pF, with uncertainty ± 1 pF Gas gap: 0.17 ±.08 mm Electrode width: 1.20 ±.01 mm 13710 58 12810

11. Capacitance vs gas gap and electrode width We would like to investigate the relationship between the values I measured and the panel’s capacitance. The geometry of the panel, specifically gas gap and electrode width, should determine the effective capacitance across electrodes. However, the contributions from other strips in the panel constitute the majority of the effective capacitance. So then capacitance at any point is really a function of panel electrode width, electrode spacing, panel dimensions, and gas gap, in addition to irregularities within the panel (i.e. degradation of electrodes).

12. Conclusion Capacitance vs position on panel: We expect effective capacitance to be greatest near the middle of the panel, where all other electrodes can contribute to effective capacitance. This seems to be the case within my error values. Capacitance of BP 1: The performance of BP 1 has been decreasing over time. The current of heavy ions generated during discharge degrades the electrode through repeated collisions. We know that the signal generated is proportional to the charge deposited on the electrode, which is proportional to the gap’s effective capacitance. Measuring greatly reduced capacitance where the panel has been in use is a measurement of decrease of panel performance.