No abstract available

[en] The physical events investigated in a Transient Hollow Cathode Discharge (THCD) are initiated by means of high voltage electric discharges ranged in low pressure, and it is characterized by an axial aperture in the cathode electrode. The main effect of the axial orifice in the cathode is to modify the geometry of the extemal applied electric field creating local conditions of ionization in the Hollow Cathode Region (HCR) previous to the occurrence of a substantial growth of the ionization processes in the interelectrode region (A-K). The ionization processes, occurring so much in the A-K region like in the HCR are mutually assisted , are the essential events which leads the final electric breakdown; both region are interconnected by means of the hollow cathode leading, from the beginning of the discharges, the existence of three distinguished ionization regime. In some previous statistical studies it was suggested that in the third identified regime would exists a competition between the ionization events due to that the temporal statistics distributions of this events would not obey to gaussian distributions. The present work attempts to show the temporal ionization events sequence which exists in the third regime in the range of 100 ns previous to the breakdown. The temporal sequence of the studied ionization events occurs in Hydrogen gas at 30 kV voltage supply in the work pressure range of 50 and 500 mTorr for different cathode apertures (C.W)

No abstract available

[en] Over the past three years, Advanced Energy Systems and Brookhaven National Laboratory (BNL) have been collaborating on the design of an Ampere- class superconducting photocathode electron gun. BNL performed the physics design of the overall system and RF cavity under prior programs. Advanced Energy Systems (AES) is currently responsible for the engineering design and fabrication of the electron gun under contract to BNL. We will report on the engineering design and fabrication status of the superconducting photocathode electron gun. The overall configuration of the cryomodule will be reviewed. The layout of the hermitic string, space frame, shielding package, and cold mass will be discussed. The engineering design of the gun cavity and removable cathode will be presented in detail and areas of technical risk will be highlighted. Finally, the fabrication sequence and fabrication status of the gun cavity will be discussed

[en] The goal of this activity has been to develop and implement S-20 photocathode processing techniques at Lawrence Livermore National Laboratory (LLNL) in order to study the physical properties of the photocathode films. The present work is the initial phase of a planned activity in understanding cathode fabrication techniques and the optical/electrical characterization of these films

[en] The UCLA rf photo-injector system has been commissioned. All of the sub-components such as the high power rf, pico-second laser, rf photo-injector cavity, diagnostics, and supporting hardware have been tested and are operational. The authors briefly discuss the performance of the various components since the details of each subsystem are very lengthy. The laser delivers a sub 4 ps pulse containing 0-300 μJ of energy per pulse. The photo-injector produces 0-3 nC per bunch with an rf induced emittance of 1.5 π(mm-mrad)

[en] Experimental and theoretical researches on the discharge mechanism. The characteristics of high-voltage hollow cathode discharge are presented. Both experimental and theoretical problems concerning the main discharge properties and the discharge mechanism are discussed. (author)

No abstract available

[en] An ion source provided with a hollow cathode discharge system is presented. The ion extraction system is designed in view of generating a beam directed towards a point of use located far from the point of ion production. Said source essentially comprises two cathodes facing each other, an anode at a continuous voltage with respect to the cathodes, a heated filament beyond the cathode on the path of the extracted beam, and a grid between said filament and cathode. The ion extraction is limited to a certain portion of the ions present inside the plasma, so as the discharge to continue to be sustained by itself. For that purpose pierced cathodes are used, with a transparency (the ratio of the hole area to the whole cathode area) not much higher than 50%

No abstract available