Immunity testing for human electrostatic discharges (ESDs) is prescribed in IEC 61000-4-2, in which an ESD generator or ESD gun is used to inject into equipment under test the discharge current through a lumped resistor from a charged lumped capacitor. In actual ESD events from a charged human, however, charges distributed on the body surface should be discharged through a spark from his/her fingertip, and therefore its situation can essentially be different from that of the ESD gun. To grasp the behavior of the discharge currents for human ESDs, using a 12 GHz digital oscilloscope we measured discharge currents caused by air discharges through the fingertip or hand-held metal bar from a charged human with respect to charge voltages from 300 V to 3 kV. Results show that at charge voltages of less than 1 kV, the fingertip contact causes discharge bursts, whose occurrence frequencies increase with decreasing the charge voltages, while the hand-held metal bar at any charge voltages makes discharges complete at a time.

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Electrostatic discharges (ESDs) due to the collision of charged metals cause serious malfunctions in high-tech information devices. In particular, a faster collision provides a more severe ESD event, while the mechanism has not fully been elucidated, though it has widely been accepted that the faster the approach speed is, the shorter the spark length becomes. In this study, to investigate this relation quantitatively, we developed a setup for electronically measuring a spark length in air discharges of ESD generators (ESD guns), and measured spark lengths at charge voltages from + 1 kV to + 8 kV with two average approaching speeds of 20 mm/s and 100 mm/s for slow and fast approach, respectively. Measured spark lengths were validated by comparing the calculated values from two different types of empirical formulae based on the Paschen's law and experimental results shown by other researchers. As a result, we found that spark lengths measured for fixed electrodes agreed well with one of the empirical formulae, and also that the approach speeds affect spark lengths, namely the spark length for fast approach was shorter than the one for slow approach. Furthermore the measured spark lengths were found to have the same tendency with respect to approach speeds and charge voltages as other researcher's results and our previous study.

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Transient characteristics and frequency spectra of impulsive electromagnetic radiation caused by ESDs were examined experimentally in order to clarify an EM radiation mechanism. The experimental system consists of a pair of spherical electrodes, a 1-18 GHz band width horn antenna and a 20 GHz bandwidth digitizing oscilloscope. Discharge voltage is less than 600 V in this experiment. As a result, the waveform duration and first peaks of the EM field radiation can be explained from a dipole antenna structure which makes a pair of spherical electrodes. Furthermore, as the excitation factors of the EM radiation from electrode elements are mentioned the current path length of the electrodes, and transient speed di/dt of discharge current. In addition, the frequency spectrum distribution of the received voltage was found to be related to the excitation path length determined by the size of the spherical electrode.

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Exponential tapered line type conical monopole antenna is proposed as a radiator of electromagnetic wave due to electrostatic discharge (ESD). The electromagnetic wave radiated by discharge such as ESD is broadband and influenced by lead lines connected to discharge electrodes. Therefore, the broadband antenna, which can lay on the electrodes to the antenna input and withstand the high voltage, is required instead of lead lines.  The proposed antenna is the conical monopole antenna having an exponential tapered line structure. The characteristic impedance of the antenna changes from 50Ω to the free space impedance according to exponential function. The return loss and input impedance of the conical monopole antenna were measured by a network analyzer in the frequency range from 300kHz to 9GHz. As a result of experiment, the return loss was less then -20dB and the input impedance was 50Ω in frequency range from 1.6GHz to 9GHz. The results of the experiment are compared with the linear tapered line type monopole antenna that the characteristic impedance changes from 50Ω to the free space impedance linearly. The return loss of the conical monopole antenna was lower than that of the linear tapered line type monopole antenna.

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This paper investigates a mechanism of faulty outputs from cryptographic modules due to intentional electromagnetic interference (IEMI) which causes information leakage in electric devices without disrupting their functions or damaging their components. We show the mechanism of fault occurrence through experiments using the faulty ciphertexts and the pulse injection to the specific round. The experimental results indicate that faulty outputs from cryptographic modules are caused by setup-time violation to the cryptographic module.

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This paper reports results of magnetic field measurements around power distribution equipment i.e. pad-mounted transformers, pad-mounted switchgears and vertical cables. Measurements were carried out in accordance with IEC 62110 which prescribes measurement and evaluation procedures of non-uniform as well as uniform magnetic fields generated by ac power systems with regard to public exposure. The average exposure level of magnetic field, corresponding to the spatial average over entire human body of magnetic field to which the individual is exposed, was evaluated for each power distribution equipment based on the measurement results. The maximum exposure level, the highest average exposure level over the area of interest, was also obtained. It was found that both exposure levels are much lower than the reference level from the ICNIRP Guidelines published in 2010.

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In electrostatic discharge (ESD) immunity tests, it has empirically been known that contact discharge currents are enhanced by the existence of small air gaps between an ESD generator and equipment under test; however, its mechanism has not been well examined so far. In this study, to clarify the phenomena, we measured discharge currents through small air gaps from 30 µm to 1 000 µm in contact discharges of an ESD generator to an IEC current calibration target. As a result, we found that multiple current peaks appear depending on the gap length and test voltage as well, which are unlikely to occur in conventional contact discharge tests. It was also found that the contact discharge current with a small gap provides a faster rise time and larger current peak in comparison with normal contact discharge tests even at the same test voltage. A circuit approach was used to qualitatively explain the peculiar finding and revealed that the stray capacitances of the discharge electrode are first charged by a contact discharge test and then the accumulated charges are abruptly discharged due to the spark that occurs across a small gap, which gives faster rise time and larger current peaks.

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Recently our EM environment is becoming more and more complicated increasingly. To investigate the immunity/susceptibility performance of electronic equipments in such an environment, basic properties of a digitally modulated rotating EM field (rotating DM-EM field) are discussed as an incident EM field on the equipment and a method to generate the rotating DM-EM field is introduced. In this paper, an FSK modulated rotating-EM field (rotating FSK-EM field) is examined as an example and two dimensional rotation of the FSK-EM field at 1 Hz is confirmed by experiment.

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Translation motion of a field-reversed configuration (FRC) plasma caused by the magnetic pressure gradient force is simulated by the 2-D resistive MHD simulation model. In the MHD code, we modeled to separate the external magnetic field and the field generated by the plasma. The translation velocity is controlled by a time-varying external magnetic field, and the volume-averaged translation velocity in our case is found to reach about 60% of the Alfvén velocity estimated by the external field and the maximum density. Axial collision processes of two FRC plasmas are also studied, and it is found that the current density at their midpoint increases rapidly when two FRCs get close to each other.

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A pulsed power generator using a semiconductor opening switch (SOS) and the other pulsed power generator using a magnetic compression method were compared for applications of pulsed streamer discharge. The resistor and equivalent circuits of the discharge load were used as the load. The SOS generator outputted higher and shorter pulsed voltage with lower energy transfer efficiency comparing with the magnetic compression generator. Therefore, if a pulsed high voltage with comparatively short width is required, the SOS generator is more suitable. However, if a pulsed high voltage with long width is required, the magnetic compression generator is more suitable because of higher efficiency. Further, the decrease of the load impedance led to decrease of the peak value and the pulse width and the increase of the energy transfer efficiency. Hence, if initial discharge impedance is high and it decreases immediately after the pulsed voltage reached the maximum, the output of high peak and short width is obtained with higher efficiency.

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Perfluorooctanesulfonic acid (PFOS) is widely used for industrial and commercial products such as foam fire extinguishers and coating agents for semiconductors because of its chemical stability and physical characteristics. However, PFOS is remarkably stable and remains in the environment. Moreover, PFOS cannot be decomposed by conventional methods such as an advanced oxidation process (AOP) that involves the use of hydroxyl radicals. In this study, a reactor for generating 21 plasmas was developed to decompose PFOS rapidly and efficiently. By using the plasma treatment, 96% of PFOS in a 1-L solution was successfully decomposed in 1200 min. By using a capacitor as the ballast element, the reactor circuit efficiency became 32% (conventional) to 95% by reducing the power loss of the ballast element. Furthermore, the decomposition reaction process of PFOS by plasma was quantitatively clarified with a simulation model of the PFOS decomposition system using the plasmas.

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Cu-Zn-Sn precursor films were prepared by spin-coating method. Copper naphthenate, zinc naphthenate, and tin octoate were used as starting materials. The precursor films were sulfurized in Ar+H₂S (10%) atmosphere at treatment temperature of 400-600°C for 90 minutes.

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