Yoshinori Taka

Cole-Cole Measurement of Dispersion Properties for Quality Evaluation of Red Wine

Cole-Cole Measurement of Dispersion Properties for Quality Evaluation of Red Wine In order to evaluate the quality of red wine, measurement of the complex relative permittivity was conducted in the frequency range from 100 MHz to 40 GHz with a network analyzer. Results showed that the Cole-Cole plot of red wine consists of a semicircle at frequencies above 1 GHz and a straight line at frequencies below 1 GHz, which come from the dispersion properties for the water solution of alcohol and ingredients peculiar to red wine, respectively. Based on the Cole-Cole plots measured for seven kinds of red wines made from the same brand of Merlot in different production years, we estimated Debye dispersion parameters to reveal that the alcohol concentration and ingredient property can simultaneously be evaluated from the parameters for the semicircle and straight line, respectively.

Transfer impedance of new-type calibration target and reconstruction of injected currents for air discharges from electrostatic discharge generators

We measured in the frequency range from 300kHz to 6GHz of the transfer impedance of a commercially available calibration target newly developed for immunity testing against electrostatic discharges (ESDs) being prescribed by the International Electrotechnical Commission. The result showed that the transfer impedance has an almost flat frequency response up to 6GHz, while resonance phenomena were still observed at frequencies around 2.5 and 5GHz. With this result, the waveforms of injected currents onto the target were reconstructed from the observed output voltages for air discharges of an ESD generator with a charge voltage of 2kV.

Reconstruction of discharge currents injected on calibration target from electrostatic discharge generators

In the present study, measurements were made in the frequency range from 300kHz to 6GHz of the transfer impedance of a commercially available calibration target used for the immunity testing against electrostatic discharges (ESDs) that the International Electrotechnical Commission (IEC) prescribes, and thereby the waveforms of discharge currents injected onto the target were reconstructed from their observed output voltages for contact and air discharges of an ESD generator with a charge voltage of 2kV. As a result, it was confirmed that the transfer impedance has an absolute value of almost 1 Ω at frequencies up to 6 GHz, while resonance phenomena were observed at frequencies around 2 and 5 GHz. This result has demonstrated that the reconstructed discharge current waveforms agree well with those of the observed voltages for the contact discharge and air discharge with slow approach, producing the current with a rise time of almost 1 ns, while the reconstructed current has a slightly small peak and gentle rising part in comparison with those of the observed voltage for the air discharge with fast approach, which gives the current within a rapid rise time of a hundred pico-seconds.

Verification of spark resistance formula for human ESD

Short-gap electrostatic discharge (ESD) events due to charged moving-objects provide a fatal electromagnetic failure to high-tech information equipment. For clarifying the mechanism, it is indispensable to elucidating the initial discharge process or spark process of ESDs. In the present study, with a 12-GHz digital oscilloscope, we measured the discharge current due to collision of a hand-held metal piece from a charged human body, and thereby derived the corresponding discharge voltage. Using two types of spark-resistance formulae proposed by Rompe-Weizel and Toepler, we verified their hypotheses assumed for spark conductivity with respect to charged voltages and collision speed. As a result, we found that both hypotheses are almost valid in the spark process, while they do not hold in the stage after the spark due to the occurrence of different types of discharges like glows and arcs.

Gap Breakdown Field Caused by Air Discharge through Hand-Held Metal Piece from Charged Human-Body

We measured the discharge currents due to air discharge through a hand-held metal piece from a charged human-body with respect to charge voltages below 1000 V. The gap breakdown fields were thereby estimated, which were validated from the Paschens law and other researchers experimental result

Further Validation of Spark-Resistance Formula Applied for Human ESD

Micro-gap electrostatic discharge (ESD) events due to a human with charge voltages below 1000 V cause serious malfunctions in high-tech information devices. For clarifying such a mechanism, it is indispensable to grasp the spark process of such micro-gap ESDs. For this purpose, two types of spark-resistance laws proposed by Rompe-Weizel and Toepler have often been used, which were derived from the hypotheses that spark conductivity be proportional to the internal energy and charge injected into a spark channel, respectively. However, their validity has not well been investigated. To examine which spark-resistance formula could be applied for human ESDs, with a 12-GHz digital oscilloscope, we previously measured the discharge currents through the hand-held metal piece from a charged human with respect to charged voltages of 200 V and 2000 V, and thereby derived the conductance of a spark gap to reveal that both of their hypotheses are roughly valid in the initial stage of sparks. In this study, to further validate the above spark hypotheses, we derived the discharge voltages in closed forms across a spark gap based on the spark-resistance formulae, and compared them with the estimated results from the measured discharge currents. As a result, we found that Rompe-Weizels formula could well explain initial spark process than Toeplers one regardless of charge voltages.

Dependence of breakdown fields on charge voltages for human ESD

Electrostatic discharge (ESD) events due to charged movement objects with low voltages give a fatal electromagnetic interference in high-tech information equipment. In order to clarify the mechanism, with a 6-GHz digital oscilloscope, we previously measured through a 50-Omega SMA connector the discharge currents due to collision of a hand-held metal piece from a charged human body from 200 V to 2000 V, and thereby estimated a gap breakdown field. As a result, we found that at charge voltages lower than 600 V breakdown fields are almost kept constant, while at charge voltages over 600 V the breakdown fields decrease with charge voltages, which could be explained from an empirical formula based on the Paschenpsilas law. In this study, with a 12-GHz digital oscilloscope, wideband measurements of the discharge currents were made through an IEC calibration target at a wide range of charge voltages from 200 V to 8000 V covering the ESD test voltages specified in the IEC standard. The corresponding breakdown fields were estimated, whose dependence on charge voltages was found to be roughly the same as that previously obtained.

Dependence of grounded metal-plate's approach speed on spark length for air discharges of electrostatic discharge generator

Electrostatic discharges (ESDs) due to the collision of charged metals cause serious malfunctions in electronic information devices. In particular, the faster collision provides the electronic devices with severer ESD events, while the underlying mechanism has not fully been elucidated, though it has been widely accepted that the approach speed affects a spark length. In this study, to investigate the dependence of the approach speed on sparks, we developed a novel setup for electronically measuring a spark length for air discharges of ESD generators (ESD guns) with a velocimeter based on laser Doppler effects, which was validated from two different types of empirical formulae derived from the Paschens law. Measurements of spark lengths were conducted by moving a grounded metal-plate to an ESD gun at three different approach speeds of 20 mm/s, 100 mm/s and 200 mm/s. The results showed that spark lengths exponentially decrease with the increase in the approach speed of the grounded plate.

Measurement of Discharge Currents due to Human-ESD

Using a 12-GHz digital oscilloscope, we have measured discharge currents through a fingertip or a hand-held metal bar from a charged human body with a charge voltage of 600 V, and have compared their discharge waveforms in conjunction with the corresponding discharge voltages, which were derived from our previously proposed equivalent circuit model.

Transfer Impedance of SMA Receptacle as Wideband Measurement Electrode for Discharge Current from Charged Human

We have derived a transfer impedance of an SMA receptacle as a wideband measurement electrode being used for discharge currents from a charged human, and have measured its frequency characteristics from 300 kHz to 20 GHz. With a 12 GHz digital oscilloscope, measurement of discharge currents through a hand-held metal bar from a charged human was also made, and thereby the injected currents on the SMA receptacle were reconstructed from the measured transfer impedance.