Evaluation program for secondary spacecraft cells: Evaluation of storage methods, open circuit versus continuous trickle charge, Sonotone 3.5 ampere-hour sealed nickel-cadmium secondary spacecraft cells

Twenty-five cells were used in a five-year test to compare, after each successive one-year storage period, the discharge and charge characteristics of charged cells on open circuit versus that of cells on continuous trickle charge. The test procedure, instrumentation, and results are described. Based on the test results, the following recommendations were made: (1) If the user's purpose will allow a rejuvenation cycle or two after a long storage period, the open circuit regime will likely give slightly greater capacity. (2) If the user's purpose demands immediately available power following a long storage period, the trickle charge method of storage is definitely the regime to use

Nondestructive test determines overload destruction characteristics of current limiter fuses

Nondestructive test predicts the time required for current limiters to blow /open the circuit/ when subjected to a given overload. The test method is based on an empirical relationship between the voltage rise across a current limiter for a fixed time interval and the time to blow

Using Commercial Off-The-Shelf Fuses in Vacuum

In the summer of 2015 during thermal vacuum testing of the Geostationary Operational Environmental Satellite-R series (GOES-R) observatory, a heater circuit that was part of the ground support equipment in the vacuum chamber developed an electrical short. The current flow through the short melted and vaporized approximately a meter of 14-gauge polytetrafluoroethylene (PTFE) insulated twisted pair copper wire. The test event was treated as a mishap, and an independent team investigated the failure. The mishap investigation team found as a contributing root cause that the test setup lacked sufficient circuit protection, and for future testing of the next three GOES-R observatories, they recommended the use of fusing or circuit interruption to protect the heater circuit wires [1]. In response to this recommendation, the GOES-R flight project traded two fusing options. One option was to locate the fuses for the wires inside the vacuum chamber, and the other was to locate the fuses external to the chamber. To support fusing inside the vacuum chamber, developmental testing of commercial off-the-shelf (COTS) fuses was initiated. Based on the heater circuit design, the testing focused on fusing 9 A at 250 V direct current (VDC) in both soft,130 Pa (1 torr), and hard, <30 mPa (2 10(exp 4) torr), vacuum conditions. If the selected fuses do not open a shorted circuit, then the test heater wires could vaporize again and cause another contamination event. If the fuses open below the required 9 A, then the spacecraft thermal vacuum testing campaign will be interrupted to open the chamber to replace test heater fuses

Evaluation program for secondary spacecraft cells: Initial evaluation tests of General Electric Company 6.0 ampere hour nickel-cadmium spacecraft cells with auxiliary electrodes for the atmospheric Explorer satellite C and D

The capacity of the cells ranged from 6.6 to 7.6 ampere hours during the three capacity tests. No voltage requirements or limits were exceeded during any portion of the test. All cells recovered to a voltage in excess of 1.193 volts during the 24-hour open-circuit portion of the internal short test. All the cells reached a pressure of 20 psia before reaching the voltage limit of 1.550 volts during the pressure versus capacity test. The average ampere/hours in and voltages at this pressure were 9.1 and 1.513, respectively. All cells exhibited pressure decay in the range of 1 to 5 psia during the last 30 minutes of the 1-hour open circuit stand. Average capacity out was 7.2 ampere/hours

Error analysis in two-terminal impedance measurements with residual correction

Residual impedance correction in impedance analyzers when using an asymmetrical test fixture needs three reference measurements, usually open circuit, short circuit, and load (meaning an impedance close to the impedance under test). This paper provides an error estimate for impedance measurements that apply a simple open/short correction in spite of using an asymmetrical test fixture. Experimental results show that the minimal error is obtained for impedance values close to the geometric mean of the short-circuit and open-circuit impedances, and that the theoretical prediction is indeed an upper limit for the actual error.Peer Reviewe

Uncertainty analysis in two-terminal impedance measurements with residual correction

Residual impedance correction in impedance analyzers when using an asymmetrical test fixture needs three reference measurements, usually open circuit, short circuit, and load (meaning an impedance close to the impedance under test). This paper provides an uncertainty estimate for impedance measurements that apply a simple open/short correction in spite of using an asymmetrical test fixture. Experimental results show that the minimal uncertainty is obtained for impedance values close to the geometric mean of the short-circuit and open-circuit impedances, and that the theoretical prediction is indeed an upper limit for the actual uncertaintyPeer Reviewe

Studies of silicon pn junction solar cells

Modifications of the basic Shockley equations that result from the random and nonrandom spatial variations of the chemical composition of a semiconductor were developed. These modifications underlie the existence of the extensive emitter recombination current that limits the voltage over the open circuit of solar cells. The measurement of parameters, series resistance and the base diffusion length is discussed. Two methods are presented for establishing the energy bandgap narrowing in the heavily-doped emitter region. Corrections that can be important in the application of one of these methods to small test cells are examined. Oxide-charge-induced high-low-junction emitter (OCI-HLE) test cells which exhibit considerably higher voltage over the open circuit than was previously seen in n-on-p solar cells are described

Correlation between pattern density and linewidth variation in silicon photonics waveguides

We describe the correlation between the measured width of silicon waveguides fabricated with 193 nm lithography and the local pattern density of the mask layout. In the fabrication process, pattern density can affect the composition of the plasma in a dry etching process or the abrasion rate in a planarization step. Using an optical test circuit to extract waveguide width and thickness, we sampled 5841 sites over a fabricated wafer. Using this detailed sampling, we could establish the correlation between the linewidth and average pattern density around the test circuit, as a function of the radius of influence. We find that the intra-die systematic width variation correlates most with the pattern density within a radius of 200 gm, with a correlation coefficient of 0.57. No correlation between pattern density and the intra-die systematic thickness variation is observed. These findings can be used to predict photonic circuit yield or to optimize the circuit layout to minimize the effect of local pattern density. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

Evaluation program for secondary spacecraft cells: Initial evaluation tests of Gulton Industries, Incorporated, 9.0 ampere-hour nickel-cadmium spacecraft cells with auxiliary electrodes for the small astronomy Satellite (SAS-C)

An evaluation test program was conducted to insure that all cells put into the life cycle program are of high quality by the screening of cells found to have electrolyte leakage, internal shorts, low capacity, or inability of any cell to recover its open-circuit voltage above 1.150 volts during the internal short test. Tests and results are described