International Symposium on Discharges and Electrical Insulation in Vacuum 

About: International Symposium on Discharges and Electrical Insulation in Vacuum is an academic conference. The conference publishes majorly in the area(s): Vacuum arc & Cathode. Over the lifetime, 2323 publications have been published by the conference receiving 9444 citations.

Multilayer ultra-high gradient insulator technology

Abstract: The authors investigate a novel insulator concept which involves the use of alternating layers of conductors and insulators with periods less than 1 mm. These structures perform many times better (about 1.5 to 4 times higher breakdown electric field) than conventional insulators in long pulse, short pulse and alternating polarity applications. They present their ongoing studies investigating the degradation of the breakdown electric field resulting from surface roughness, the effect of gas pressure and the performance of the insulator structure under bipolar stress. Further, they present their initial modeling studies.

Discharge characteristics of the spherical inertial electrostatic confinement (IEC) device

Abstract: The University of Illinois inertial electrostatic confinement (IEC) device provides 10/sup 7/ 2.5 MeV D-D neutrons/second when operated with a steady-state deuterium discharge at 70 kV. Being compact and lightweight, the IEC potentially represents an attractive portable neutron source for activation analysis applications. The plasma discharge in the IEC is unique, using a spherical grid in a spherical vacuum vessel with the discharge formed between the grid and the vessel wall, while the -70 kV grid (cathode) also serves to extract high-energy ions. Two key features of the IEC discharge are discussed: 1) the breakdown voltage characteristics as a function of pressure-grid/wall distance (pd), and 2) the formation of ion "microchannels" that carry the main ion flow through grid openings.

Cathode processes in free burning and stabilized by axial magnetic field vacuum arcs

Abstract: Collective behavior of the cathode spots (CS) has been investigated in free burning and stabilized by axial magnetic field (AMF) vacuum arcs. Experiments carried out proved previously discovered phenomenon of CS group formation in free burning arc to be a general phenomenon for a short high-current vacuum arc. The dependency of CS group size in the developed are on arc current for different contact materials has been analyzed. Application of AMF with even relatively low intensity strongly affects on cathode processes. In short arcs, it hinders formation of the CS group and consequently reduces thermal stress applied to the electrodes. It has been revealed that high current vacuum arc under the action of AMF can exist only at current densities exceeding certain minimal value that depends on AMF intensity, contact gap, and does not depend on current itself. The dependency of this minimal (or normal) current density on AMF intensity has been studied for short and long vacuum arcs. A qualitative model of the cathode spot dynamics has also been proposed.

Mathematical modeling of the high frequency behavior of vacuum interrupters and comparison with measured transients in power systems

Abstract: When the gap length of a vacuum switch at current zero is too short (i.e. contacts open shortly before current zero), high frequency transients, known as multiple reignitions or virtual current chopping, may occur under certain network conditions. In order to estimate the probability of such transients a mathematical vacuum breaker model, based on numerous measured data, has been developed. It is able to simulate the HF-behaviour in single or three phase networks. To verify the abilities of the breaker model, complex measurements of the interruption of a modern 11 kV dry type transformer with a vacuum breaker under no-load conditions have been carried out. A comparison between the measured data and the results of the simulations, which require an equivalent HF-network for all involved devices (especially the transformer), is presented.

Technological progress of axial magnetic field vacuum interrupters

Abstract: New methods have been developed for investigating vacuum arcs applied to the improvements of vacuum interrupter electrodes. Electrode surface temperature measurements reveal the anode surface melting condition at the current interruption and its influence on interruption capability, and a digital image processing technology gives us a clear understanding of the arcing phenomenon. Measurements and test results have shown the advantages of axial magnetic field electrodes in increasing the interruption capability of vacuum interrupters. It is confirmed that axial magnetic field electrodes are superior to other types of electrodes, and we believe that these new investigation methods promote the optimization of the electrode structure and the realization of higher voltage and current rating vacuum interrupters.