Arthur B. Campbell

Characterization of single-event upsets in a flash analog-to-digital converter (AD9058)

Single-event upsets were observed in a flash analog-to-digital converter (AD9058) included as part of a radiation effects experiment on board a satellite. The origins of the upsets were identified using a pulsed laser and confirmed by exposing the AD9058 to both heavy ions and protons at accelerator facilities. The salient result of this work is that the single-event-upset cross-section depends on the value of the analog input but does not appear to depend on clock frequency. Therefore, using a single value for the analog input during ground testing may give an incorrect estimate of the error rate expected during operation in space where the input can vary over the full voltage range.

Angular dependence of multiple-bit upsets induced by protons in a 16 mbit DRAM

The number of double-bit upsets induced by protons in a 16 Mb DRAM was found to increase with angle of incidence. The increase was greater for intermediate energy (63 MeV) protons than for high-energy (198 MeV) protons. An explanation is offered and the results of a calculation using the CUPID program agree with the observations.

Validity of using a fixed analog input for evaluating the SEU sensitivity of a flash analog-to-digital converter

The single-event upset (SEU) rate in a flash analog-to-digital converter (ADC) AD9058 on board a space experiment varied by more than an order of magnitude, depending on the input. A pulsed laser aided in elucidating the reasons, which were found to be the result of the unique design of the AD9058.

Single-chip dosimeters to accompany photometric systems flown in space

Modern photometer systems need to be accompanied by dosimeters that monitor exposure to total ionizing dose, ultraviolet light, and the flux of particles with linear energy transfer above some threshold value. These detectors should minimize space, weight, power, cost, and telemetry. A new approach is described in which single-chip, two-chip, or three-chips systems incorporated into the photometers interface circuits measure the above while including information on the status of charge trapping in oxides and thermal noise at p-n junctions.

Applications of Ion Implantation to Metallic Corrosion

The Bureau of Mines is conducting research on the corrosion behavior of alloys formed by ion implantation with the ultimate goal of conserving strategic alloying materials such as chromium and nickel. These alloys were fabricated by the implantation of 25-keV chromium, nickel, and aluminum ions into polycrystalline iron to fluences ranging from 1 to 5 × 1016 ions/cm2. The alloy distribution as a function of depth (depth profile) has been determined for the ion-implanted alloys, and the results have been compared with theoretical predictions. Changes in the profiles due to annealing were investigated, and the values that were obtained for the diffusion coefficients were compared with published values for the volume diffusion coefficients. The resistance of these alloys to environmental attack has been evaluated both by determining their anodic polarization behavior under potentiostatic conditions in a buffered boric acid solution and by determining their gaseous oxidation characteristics. Results of the electrochemical studies have shown that the general corrosion resistances for the ion-implanted alloys were comparable to those of nominally equivalent bulk alloys and that their pitting corrosion resistance was superior to that of iron, although generally not as good as that for most equivalent bulk alloys. Gaseous oxidation studies have shown that ion-implanted and bulk iron-chromium alloys exhibit essentially identical oxidation kinetics, with a much higher rate of oxidation observed for iron. The influence of radiation damage on the gaseous oxidation of iron has been studied by implanting iron ions into iron.