From ernie@physics.carleton.ca Tue Sep 9 16:38:01 2003 Date: Tue, 9 Sep 2003 12:45:48 -0400 (EDT) From: Ernie Neuheimer To: Madhu@physics.carleton.ca Cc: Kirsten Sachs Subject: Measurement of Dupont XC Kapton Resistive Film with Applied Voltage Gradient, Part Two. X-IMAPbase: 1426689751 1 Status: O X-Status: X-Keywords: X-UID: 1 Madhu, As requested, I measured the resistance of Dupont Kapton type XC carbon particulate-loaded film with voltage gradient for values from 1 mV/cm to 100V/cm using the same five resistive strips of length 24 cm and width 2cm (i.e., 12 squares long) which were the samples in the report of 2 September. This extends the range of measurements into lower voltage gradient with good overlap. Applied voltage gradients of the earlier report ranged from about 41.6mV/cm to 125V/cm. These range from 1mV/cm to 100V/cm. Applied voltage was measured with a Keithley model 2000 and current was measured with another model 2000 connected voltmeter monitoring the strip current using a 10K, 1% MF resistor as shunt. At the low voltage gradient end of the range, current was measured with only single digit +/- 0.5 nanoAmpere accuracy but results were consistent enough over the 5 strips to be significant. [The measurements of 2 September used a Keithley as ammeter where accuracy, at the level of the lowest .13 microA readings is about 19% (accuracy + resolution)] The results are tabled below: Appl. Voltage I. I. I. I. I. Volt. Gradient Strip 1 Strip 2 Strip 3 Strip 4 Strip 5 (mV or (mv/cm) (nA) (nA) (nA) (nA) (nA) V.) (HP PS) 24.53mV 1 3. 3. 3. 3. 3. 48.21 2 7. 7. 7. 7. 7. 120.4 5 19. 19. 19. 19. 19. 240.0 10 39. 39. 38. 38. 38. 480.3 20 78. 78 77. 76. 77. 1.200V. 50 196. 198. 192. 192. 195. 2.399 100 393. 397. 386. 386. 390. 4.800 200 788. 795. 774. 769. 782. 12.00 500 1973. 1994. 1925. 1923. 1958. 24.00 1000 3941. 3969. 3869. 3852. 3920. -24.00 -1000 -3927. -3965. -3871. -3847. -3905. (Hrsn. 23.99 1000 3947. 3971. 3875. 3844. 3916. PS) 48.00 2000 7902. 7976. 7729. 7747. 7908. 120.0 5000 1988. 2014. 1955. 1958. 1994. 240.0 10000 4028. 4089. 3968. 3974. 4047. 280.0 20000 8262. 8388. 8151. 8157. 8300. 1200. 50000 21990. 22340. 21730. 21760. 22090. 2400. 100000 48160. 48660. 47180. 47480. 47510. [The above measurement at -1000mV/cm (reversed polarity) was made to show the absence of any 'rectifying' feature in the copper/adhesive/foil sandwich. The repeated measurement with the higher voltage Harrison power supply was made for repeatability and continuity reasons.] Resistance of foil was calculated using the average value of the strip current at that voltage gradient: Voltage Gradient Avg. Current Calculated Resistance (milliVolts/cm.) (nAmp.) (MegOhms) 1 3 .333 2 7 .286 5 19 .263 10 38.4 .260 20 77.2 .259 50 195 .256 100 390 .256 200 782 .256 500 1955 .256 1000 3910 .256 -1000 -3903 .256 1000 3909 .256 2000 7852 .255 5000 1989 .251 10000 4021 .249 20000 8252 .242 50000 2198 .227 100000 4780. .209 These values were plotted on a semi-log graph along with values from the previous report of September 2, converted to corresponding voltage gradient. The results are in agreement given the relative accuracy of the two measurement methods. A copy of the graph will be attached to this report presented at the next TPC meeting. Conclusion: The resistance of the Dupont Kapton XC film is 0.256 MegOhm per cm and constant for voltage gradients from 1mv/cm to about 10 V/cm. after which it seems to fall off.