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Four-terminal connector for measuring resistance of a pyrotechnic initiator

A four-terminal electrical connector device (40) for testing and measuring unknown resistances of initiators (11) used for starting pyrotechnic events aboard a Space Transportation System. The testing device minimizes contact resistance degradation effects and so improves the reliability of resistance measurement taken with the device. Separate and independent voltage sensing (19) and current supply (20) circuits each includes a pair of socket contacts (13-16) for mating engagement with the pins (17,18) of the initiator. The unknown resistance that is measured by the device is the resistance of the bridgewire (23) of the initiator which is required to be between 0.95 and 1.15 ohms

Four-terminal electrical testing device

The invention relates to a four-terminal electrical connector device for testing and measuring unknown resistances of initiators used for starting pyrotechnic events aboard the space shuttle. The testing device minimizes contact resistance degradation effects and so improves the reliability of resistance measurements taken with the device. Separate and independent voltage sensing and current supply circuits each include a pair of socket contacts for mating engagement with the pins of the initiator. The unknown resistance that is measured by the device is the resistance of the bridgewire of the initiator which is required to be between 0.95 and 1.15 ohms

Individual Practices to Increase the Graduation Rate of African American Students at Predominantly White Colleges and Universities

African American students face a number of institutional barriers when admitted to Predominantly White Colleges and Universities (PWCUs). Many of the obstacles they encounter are related to historical racism, stereotypes, and prejudices embedded in the culture of these institutions. Even though the enrollment of African American students at these institutions continues to increase, their completion rate remains low. While past studies have examined institutional strategies to increase African American graduation rate, they have failed to provide recommendations on the individual level for these students to practice. This article explores an important questions: What individual strategies are important for African American students to practice in an effort to graduate from PWCUs? Using semi-structured interviews of tenured Africam American faculty at PWCUs, ten recommendations were proposed to practice

High-density Au nanorod optical field-emitter arrays

We demonstrate the design, fabrication, characterization, and operation of high-density arrays of Au nanorod electron emitters, fabricated by high-resolution electron beam lithography, and excited by ultrafast femtosecond near-infrared radiation. Electron emission characteristic of multiphoton absorption has been observed at low laser fluence, as indicated by the power-law scaling of emission current with applied optical power. The onset of space-charge-limited current and strong optical field emission has been investigated so as to determine the mechanism of electron emission at high incident laser fluence. Laser-induced structural damage has been observed at applied optical fields above 5 GV m[superscript −1], and energy spectra of emitted electrons have been measured using an electron time-of-flight spectrometer.United States. Defense Advanced Research Projects Agency (Contract N66001-11-1-4192)Gordon and Betty Moore Foundatio

Microbunching and Beam Break Up in DUV FEL Accelerator

We present the results of electron beam longitudinal modulation studies in the DUV-FEL accelerator. For bunch length determination we used the 'zero-phasing' method, based on a measurement of the chirped electron bunch energy spectra. The measurements revealed a spiky structure in the longitudinal phase space [1]. A model based on space charge effect is considered [2] to explain of the obtained phenomena. The analysis of the energy spectra has shown a sensitivity of the structure to the electron beam peak current, energy and longitudinal non-uniformity of the RF gun drive laser. Analytical calculations have demonstrated a qualitative agreement with experimental observations. Several experiments have been made to compare with theory; measured results are reviewed in this paper. The obtained effect is briefly discussed in relation to high brightness accelerators