Performance of alkaline battery cells used in emergency locator transmitters

The characteristics of battery power supplies for emergency locator transmitters (ELT's) were investigated by testing alkaline zinc/manganese dioxide cells of the type typically used in ELT's. Cells from four manufacturers were tested. The cells were subjected to simulated environmental and load conditions representative of those required for survival and operation. Battery cell characteristics that may contribute to ELT malfunctions and limitations were evaluated. Experimental results from the battery cell study are discussed, and an evaluation of ELT performance while operating under a representative worst-case environmental condition is presented

Atomic oxygen beam source for erosion simulation

A device for the production of low energy (3 to 10 eV) neutral atomic beams for surface modification studies is described that reproduces the flux of atomic oxygen in low Earth orbit. The beam is produced by the acceleration of plasma ions onto a negatively biased plate of high-Z metal; the ions are neutralized and reflected by the surface, retaining some fraction of their incident kinetic energy, forming a beam of atoms. The plasma is generated by a coaxial RF exciter which produces a magnetically-confined (4 kG) plasma column. At the end of the column, ions fall through the sheath to the plate, whose bias relative to the plasma can be varied to adjust the beam energy. The source provides a neutral flux approximately equal to 5 x 10(exp 16)/sq cm at a distance of 9 cm and a fluence approximately equal to 10(exp 20)/sq cm in five hours. The composition and energy of inert gas beams was diagnosed using a mass spectometer/energy analyzer. The energy spectra of the beams demonstrate energies in the range 5 to 15 eV, and qualitatively show expected dependences upon incident and reflecting atom species and potential drop. Samples of carbon film, carbon-based paint, Kapton, mylar, and teflon exposed to atomic O beams show erosion quite similar to that observed in orbit on the space shuttle

Characterization of a 5-eV neutral atomic oxygen beam facility

An experimental effort to characterize an existing 5-eV neutral atomic oxygen beam facility being developed at Princeton Plasma Physics Laboratory is described. This characterization effort includes atomic oxygen flux and flux distribution measurements using a catalytic probe, energy determination using a commercially designed quadrupole mass spectrometer (QMS), and the exposure of oxygen-sensitive materials in this beam facility. Also, comparisons were drawn between the reaction efficiencies of materials exposed in plasma ashers, and the reaction efficiencies previously estimated from space flight experiments. The results of this study show that the beam facility is capable of producing a directional beam of neutral atomic oxygen atoms with the needed flux and energy to simulate low Earth orbit (LEO) conditions for real time accelerated testing. The flux distribution in this facility is uniform to +/- 6 percent of the peak flux over a beam diameter of 6 cm

Application of Self-Assembled Monolayers to InGaZnO Thin Film Transistors

Investigations on the application of self-assembled monolayers (SAM) to indium gallium zinc oxide (IGZO) thin film transistors (TFT) for fabrication and channel modification are presented. The back channel of IGZO thin film transistors can be modified by the absorption of self-assembled monolayers. The electrical properties of the IGZO exposed back channel are sensitive to surface chemistries and can be tailored using SAMs. Chemistry at the back channel interface alters device performance. The back channel surface sensitivities can be used in applications for chemical sensing TFTs. IGZO TFTs with and without octadecyl phosphonic acid applied to the back channel with varied channel thicknesses (10-50 nm) were examined. TFT parameters, such as, turn-on voltage, hysteresis, mobility, subthreshold swing, and current on/off ratio were evaluated by current-voltage electrical measurements. The use of electrohydrodynamic ink jet (EHDP) printing as non-contact method for patterning etch resists with sub-10 μm features was demonstrated for fabrication of IGZO TFTs. EHDP uses an electric field to generate ink droplets that can be smaller than the nozzle diameter. EHDP was used for depositing a self-assembled monolayer, n-hexyl phosphonic acid (HPA), and photoresist, SU8, as etch resists for patterning the IGZO TFT channel. Drop on demand printing is accomplished by overlapping of discrete droplets to form the desired feature. The optimal ink formulations and EHDP parameters were determined for each ink. Parameters were optimized for producing the smallest, uniform printed features. Bottom gate IGZO TFTs were fabricated by plasma sputtering IGZO onto a SiO₂/Si substrate. The IGZO TFT channels were patterned by printing HPA or SU8 ink as the etch resist, and using HCl as the etch solution. Indium tin oxide source and drain were deposited over the patterned channel using plasma sputtering. The electrical performance of IGZO TFTs patterned using HPA and SU8 were compared and evaluated using I-V electrical measurements. Drop on demand printing offers a high-speed, low cost route to TFT fabrication and manufacturing. The long narrow channels produced have applications for TFT sensor technologies. EHDP was shown to be capable of printing etch resists for the patterning and fabrication of IGZO TFTs on the scales relevant for digital displays

A ground-based experimental test program to duplicate and study the spacecraft glow phenomenon

The use of a plasma device, the Advanced Concepts Torus-I, for producing atoms and molecules to study spacecraft glow mechanisms is discussed. A biased metal plate, located in the plasma edge, is used to accelerate and neutralize plasma ions, thus generating a neutral beam with a flux approx. 5 x 10 to the 14th power/sq cm/sec at the end of a drift tube. Our initial experiments are to produce a 10 eV molecular and atomic nitrogen beam directed onto material targets. Photon emission in the spectral range 2000 to 9000 A from excited species formed on the target surface will be investigated

Scaling of the Transient Hydroelastic Response and Failure Mechanisms of Self-Adaptive Composite Marine Propellers

The load dependent deformation responses and complex failure mechanisms of self-adaptive composite propeller blades make the design, analysis, and scaling of these structures nontrivial. The objective of this work is to investigate and verify the dynamic similarity relationships for the hydroelastic response and potential failure mechanisms of self-adaptive composite marine propellers. A fully coupled, three-dimensional boundary element method-finite element method is used to compare the model and full-scale responses of a self-adaptive composite propeller. The effects of spatially varying inflow, transient sheet cavitation, and load-dependent blade deformation are considered. Three types of scaling are discussed: Reynolds scale, Froude scale, and Mach scale. The results show that Mach scaling, which requires the model inflow speed to be the same as the full scale, will lead to discrepancies in the spatial load distributions at low speeds due to differences in Froude number, but the differences between model and full-scale results become negligible at high speeds. Thus, Mach scaling is recommended for a composite marine propeller because it allows the same material and layering scheme to be used between the model and the full scale, leading to similar 3D stress distributions, and hence similar failure mechanisms, between the model and the full scale