Measurement of AC Ion Current from Ionizer by Using Faraday Cage
AC ionizer with high frequency became more common in semiconductor industries. Neutralization mechanism of such equipment is, however, not well understood because the measurement of extremely small ion current is interfered by AC induction. Our attempt is to use the Faraday cage that is directly connected to an AC ionizer. At frequencies of 1 Hz and 10 Hz, clear pulse shape ion currents were measured. The amounts of transported charges increase with both applied voltage and pressure. The effect of pressure is more significant than voltage. At higher frequency, the measured current changes from pulse to sinusoidal shape. From the delay time of 1 kHz, the average air velocity between the needle and Faraday cage was calculated. From DC corona measurement inside the nozzle, it became clear that the portion of transported charge to the Faraday cage is quite small.
Balanced static elimination in variable ion mobility environments
Electrical ionizers with point-to-point and point-to-plane electrode arrangements were evaluated for use in static elimination systems. Elevated temperature tests to 433 K were done in air, while reduced temperature tests to 213 K were done in liquid nitrogen vapors. Balanced static elimination was obtained throughout the temperature range by controlling the ratio of the potentials on the positive and negative emitters, and allowing large free-electron currents from the negative emitters in the nitrogen environment. The charge-decay times were continuous through the nitrogen-to-air transition and dependent upon temperature as exp(const/kT). Under balanced conditions, the ratio of charge-decay times for negatively-charged and positively-charged targets increased from about 1.1 at 213 K to 1.4 at 323 K, and returned to about 1.0 at 433 K. In air, the charge-decay times at constant negative emitter current decreased and their ratio approached unity with increasing superficial flow in the chamber. Nitrogen injection about the emitters primarily influenced static elimination when gas circulation in the chamber was otherwise small. Separate control of positive and negative carrier generation is essential to achieve balanced static elimination in industrial applications.
Data Driven Policy: The Case for Certification Research
This article describes the program of research being implemented to investigate the outcomes of certification in the U.S. and Canadian workforce and its relevance to the goal of providing policy makers with pragmatic, action-oriented recommendations. Such recommendations encompass policy issues of workforce production, regulation, distribution, financing, and oversight of credentialing organizations. Few studies exist to substantiate the association between certification credentialing and practice outcomes, thereby leaving policy makers, consumers, and nurses in a vacuum when pushed to protect the public through the credentialing vehicles. The Nursing Credentialing Research Coalition (NCRC) has embarked on a research program that will reveal the relationship between certification and its influence on a nurse’s personal, professional, and practice characteristics as well as those judged by consumers and employers. Selected findings and implications for policy are described. Certified nurses’ reports of early interventions for complications are important quality measures for policy.