Massive conductor impedance and peculiarities of transients in electrical circuits with massive conductors of pulsed power facilities
At a small skin depth the electromagnetic field in conductors can be defined by the boundary layer method. The derived asymptotic solution makes it possible to determine the expansion in a series of the voltage drop across massive conductors. In this expansion the first term describes the limiting solution with infinite conductivity and corresponds to self-induction electro-motive force (EMF) of the external magnetic field or voltage drop across external inductance of massive conductors. Asymptotic correction of the first-order approximation corresponds to the fraction of the voltage drop calculated under the impedance boundary conditions on the surface of the conductors. The second-order correction takes into account the curvature of the conductor surface and inhomogeneity of the external magnetic field and varies in time directly as does current in the conductors, i.e. as in the case with voltage drop across a usual resistor. Such approximation establishes the relation between current and voltage drop on massive conductors, which can be included into the Kirchhoff’s equations for analysis and calculation of the transients in the circuits with massive conductors. The purpose of the paper is consideration of the peculiarities of the transients in electrical circuits, the methods of measurement of the massive conductor parameters, as well as the methods of the transients calculations in the time domain, which use the asymptotic representation of the voltage drop on massive conductors.
Conceptual design of 2 MJ capacitive energy storage
Abstract The conceptual design of the capacitive energy storage intended for operation in laboratory conditions is considered. This capacitive energy storage includes the capacitor cells of 200 kJ stored energy, each incorporating one self-healing high-energy-density capacitor, one semiconducting switch unit on the basis of Light Triggered Thyristors (LTT) and the pulse diodes, as well as the toroid inductor. Power supply of the capacitive energy storage is provided by high voltage (HV) 3 × 10 kV, 50 Hz industrial electrical network, using the HV power transformer and phase-controlled rectifier. Special design for the capacitor cell and the module of capacitor cells is proposed, which provides easy access to all components of the capacitor cells during operation and maintenance. Control system of the capacitive energy system has a hierarchic structure and includes programmable logic controller (PLC), programmer for non-synchronous triggering of capacitor cells discharges and data acquisition system.
X-rays and photocarcinogenesis in hairless mice
It is well known that excessive X-ray radiation can cause non-melanoma skin cancers. With the increased incidence of sun-related skin cancer there is a need to investigate the combination of sunlight and X-rays. Immunocompetent C3.Cg/TifBomTac mice (n = 298) were divided into 12 groups. Mice were irradiated with 12, 29 or 50 kV X-rays. The mice received a total dose of 45 Gy. They were irradiated with 3 SED simulated solar radiation (SSR) either before or after irradiation with X-rays. The groups irradiated with X-rays alone, 0, 3, 9 and 10 mice (0, 12, 29 and 50 kV, respectively) developed squamous cell carcinoma. In the groups irradiated with SSR after X-rays the development of tumours was significantly faster in the 50 kV group than in the corresponding control group (175 vs. 194 days, p < 0.001). In the groups irradiated with SSR prior to the X-ray radiation the development of tumours was significantly faster in the 29 and the 50 kV groups than in the corresponding control group (175 vs. 202 days, p < 0.001 and 158 vs. 202 days, p < 0.001, respectively). In conclusion, X-ray radiation alone is a weak carcinogen in hairless mice. There is an added carcinogenic effect if X-ray radiation is given on prior sun-exposed skin or if the skin is sun-exposed after X-rays. We still believe that X-ray radiation is a safe and effective therapy for various dermatological diseases but caution should be observed if a patient has severely sun-damaged skin or has a high-risk sun behaviour.