It can be seen from Fig that when the

It can be seen from Fig. 9 that, when the operating voltage reaches 2000 V (about 88.5% of SBV), the minimum TD2 is 9.6 ns, and the maximum TD2 is 12.8 ns. When the operating voltage is changed from 1600 V (about 70% of SBV) to 2000 V, TD2 is less than 30.2 ns. When it is below 1600 V, TD2 increases rapidly. So it\'s reasonable for switch to work at voltage between 70% and 90% of its SBV.
Inductance calculation It is difficult to depict the complex breakdown process of an insulating medium (gas, liquid or solid). The capacitor discharge circuit shown in Fig. 6 is treated as a simple RLC circuit. In the circuit, C is the capacitor and the capacitance is 0.22 μF, L is the lumped inductance of the circuit which is comprised of the inductances of capacitor, wires, switch and all the soldering points, and R is the lumped resistance of the circuit which consists of equivalent series resistances of capacitor, switch and wires. When L and R are treated as constants, the circuit can be described by Eq. (1)where U0 is the initial voltage of capacitor. Also the current can be calculated from Eq. (1)where The lumped R and L can be estimated form Eq. (2), which are expressed by Eqs. (3) and (4)where I1max is the first peak current value, I2max is the second peak current value, and T1 is the first discharging fiin of current waveform. All the three parameters can be obtained from the current waveform, as shown in Fig. 10. Fig. 10 shows the current traces of the switch discharge circuit. The capacitor is charged to 3000 V when the spark gap between the main electrodes is 1.5 mm. And the capacitor is charged to 2000 V when the spark gap between the main electrodes is 1.0 mm. The first peak current value, the current rise time, the second peak current value and the first discharging cycle can be obtained from the current waveforms in Fig. 10. According to Eqs. (3) and (4), the lumped inductance and resistance are estimated to be 76.7 nH, 0.113 Ω (d = 1.5 mm) and 73.2 nH, 0.127 Ω (d = 1.0 mm), respectively. In the absence of a switch, the calculated inductance of the total circuit is 64.3 nH (±10%). Therefore the switch inductances of metal foil switches with different gaps are estimated to be 12.4 nH (d = 1.5 mm) and 8.9 nH (d = 1.0 mm), respectively. The discharge properties of metal foil switch were compared with those of a commercial stereo switch. The parameters of I1max, I2max, T1 and t1max are listed in Table 1. The I1max values of the two switches are comparative. The lumped inductance could be calculated from Eq. (4). The inductance of the metal switch is lower than that of commercial stereo switch. The time of first peak current t1max and the first discharging cycle T1 are shorter. In summary, the use of metal foil switch is beneficial to improve the energy utilization of EIFS (exploding foil initiator system).
Conclusions
Introduction Many approaches have been found to control the cylinder wake [1–3]. Some of them do not need the energy input called passive control, such as the use of splitter plates behind a circular cylinder or the addition of secondary cylinder in the wake etc. Some of them need the energy input called active control, such as rotary oscillation control of a cylinder wake, sound wave disturbance, suction and blowing, thermal effect and so on. For active control, the energy input for flow field can be adjusted based on the condition of flow field, viz. feedback control which is more useful. Using an electromagnetic field control the flow on the boundary layer is an active control approach which is easy to change the direction of Lorentz force and achieve the feedback control, even for MEMS system of concern. In the middle of the 20th century, the control of electrolyte solution with Lorentz force was desired. Gailitis [4] developed an electro-magnetic actuator consisting of alternating pairs of electrodes and magnets to create a stream wise Lorentz force in weakly conductive fluids which can modify the structures of boundary layer and wake. Weier et al. [5] presented the results from experiment on the control of the flow around a cylinder by means of electromagnetic force. A circular cylindrical test body was covered with electrodes and magnets which were used to create the Lorentz force parallel to the body surface, and the suppressing effect of Lorentz force for flow separation and Karman vortex streets have been confirmed. Crawford [6] discussed the distribution of electromagnetic field and Lorentz force. The mechanism of drag reduction has been investigated deeply through the experiment and numerical simulation in our research. Moreover, the control of cylinder wake is optimized with the nonlinear optimal control theory [7–9]. A report on the experimental study of lift amplification and vibration suppression with Lorentz force, especially for the transient control process, has been found.