Cathode Panel Research Articles

Fully Vacuum-Sealed Diode-Structure Addressable ZnO Nanowire Cold Cathode Flat-Panel X-ray Source: Fabrication and Imaging Application.

A fully vacuum-sealed addressable flat-panel X-ray source based on ZnO nanowire field emitter arrays (FEAs) was fabricated. The device has a diode structure composed of cathode panel and anode panel. ZnO nanowire cold cathodes were prepared on strip electrodes on a cathode panel and Mo thin film strips were prepared on an anode panel acting as the target. Localized X-ray emission was realized by cross-addressing of cathode and anode electrodes. A radiation dose rate of 10.8 μGy/s was recorded at the anode voltage of 32 kV. The X-ray imaging of objects using different addressing scheme was obtained and the imaging results were analyzed. The results demonstrated the feasibility of achieving addressable flat-panel X-ray source using diode-structure for advanced X-ray imaging.

Evaluating a multi-panel air cathode through electrochemical and biotic tests

To scale up microbial fuel cells (MFCs), larger cathodes need to be developed that can use air directly, rather than dissolved oxygen, and have good electrochemical performance. A new type of cathode design was examined here that uses a “window-pane” approach with fifteen smaller cathodes welded to a single conductive metal sheet to maintain good electrical conductivity across the cathode with an increase in total area. Abiotic electrochemical tests were conducted to evaluate the impact of the cathode size (exposed areas of 7 cm2, 33 cm2, and 6200 cm2) on performance for all cathodes having the same active catalyst material. Increasing the size of the exposed area of the electrodes to the electrolyte from 7 cm2 to 33 cm2 (a single cathode panel) decreased the cathode potential by 5%, and a further increase in size to 6200 cm2 using the multi-panel cathode reduced the electrode potential by 55% (at 0.6 A m−2), in a 50 mM phosphate buffer solution (PBS). In 85 L MFC tests with the largest cathode using wastewater as a fuel, the maximum power density based on polarization data was 0.083 ± 0.006 W m−2 using 22 brush anodes to fully cover the cathode, and 0.061 ± 0.003 W m−2 with 8 brush anodes (40% of cathode projected area) compared to 0.304 ± 0.009 W m−2 obtained in the 28 mL MFC. Recovering power from large MFCs will therefore be challenging, but several approaches identified in this study can be pursued to maintain performance when increasing the size of the electrodes.

Effect of the deposition parameters on the voiding propensity of solder joints with Cu electroplated in a Hull cell

A quantitative study of the impact of key Cu plating parameters on the voiding propensity of solder joints with Cu electroplated in a commercially available plating solution (CAPS) is performed first on 0.3 cm2 Cu rotating disk electrode. It is shown that similar to samples plated in a generic plating solution (GPS) containing bis(3-sulfopropyl) disulfide, polyethylene glycol, and Cl− ions, void-prone samples are deposited predominantly at higher overpotentials, in the range from positive to −0.20 V. In the second part, a Hull cell with 46 cm2 cathode is used to scale up the voiding study in both, GPS and CAPS. It is demonstrated that plating conditions could be chosen in a way to generate both, void-prone and void-proof Cu on the same cathode panel. Thus, the controlled voiding propensity illustrated for the first time in a prototype of industrial Cu plating helps in realizing the sporadic nature of the voiding phenomenon.

Fabrication of Combined Type Insulation Wall in a Field Emission Display with Carbon Nanotube Emitters

Using insulation slurry as material, the combined type insulation wall was developed with the high-effective screen-printing process. Two parts were mainly included for the combined type insulation wall, which was the lower insulation wall prepared on the cathode panel and the upper insulation wall fabricated on the anode panel, respectively. The fabricated combined type insulation wall possessed better insulation performance, and was used to separate the cathode and anode panel. Using carbon nanotube as cathode material, the field emission display with the combined type insulation wall was fabricated, and the detailed manufacture process was also presented. The sealed field emission display showed high luminance brightness, stable emission current and good field emission properties.

Status of triple GEM muon chambers for the LHCb experiment

Muon triggering and offline muon identification are fundamental requirements for the LHCb experiment, which will begin to take data at the start-up of the LHC machine. The identification of muon particles and an estimate of the transverse momentum ( Δ p T / p T ∼ 20 % ) in the near-beam area of the first muon station is achieved by a set of 12 double triple-GEM detectors which covers an area of about 0.6 m 2 . Since b-quark production is peaked in the forward direction, GEM detectors will trigger about 20% of muons from B-particle decays. In this paper the results of the detector quality checks on anode and cathode panels planarity, GEM foil HV test, chamber gas leak and gain uniformity are presented. The performance of a chamber, composed of two triple-GEM detectors logically OR-ed, has been measured in a recent test beam at the SPS, with particle bunches with a time structure of 25 ns similar to the LHC running conditions. In this test the final front-end electronics and the final LHCb DAQ have been used. This result demonstrates that the detector can achieve the required performances (efficiency larger than 96%) at a detector gain of 4000, thus ensuring a long detector lifetime in the harsh LHCb environment.

Quality tests of the LHCb muon chambers at the LNF production site

The performance demanded for the Level-0 trigger of LHCb imposes very stringent requirements on the quality of the muon chambers. These chambers must pass a series of tests before being mounted in the experimental setup. The six tests adopted for the quality control of the chambers produced at the Laboratori Nazionali di Frascati (LNF) are described. After the wires are wound and glued on a cathode panel, the wire pitch is measured by two digital cameras with a precision of about 20 mum. The mechanical tension of the wire is deduced from its mechanical resonance frequency measured by an automated system based on a digital electrostatic method. The wire tension is obtained with a precision of about 1%. Once all elements are assembled, the gas tightness of a chamber is verified by monitoring the decrease rate of an overpressure applied to it. After a suitable high-voltage conditioning, the dark current is recorded and the gas gain uniformity of the chamber is measured using a collimated 137Cs source which can be moved over the chamber surface. Finally, the detector is fully equipped with the front-end electronics, and its detection efficiency is tested with cosmic rays

Use of barium cold cathodes for low voltage DC-gas discharge color display panels

A technique for providing barium cold cathodes in a dc-gas discharge color display panels has been developed. A 21 × 111 cell green panel, fabricated in accordance with this technique, yielded a maintenance voltage of 88 ± 8 V. This value is approximately ⅓ that for conventional nickel cathode panels, resulting in a threefold increase in luminous efficiency.

Dynamic Measurement of Current Distribution in the Hull Cell

SummaryThe usual method of determining the secondary or true current distribution in a Hull cell has been to use cathodes divided into strips. There are some practical, and theoretical difficulties associated with this technique which have been largely eliminated by the use of an apparatus which sweeps a reference probe back and forth across the cathode panel. The current distribution is calculated by correlating the results with polarization data. It is simple to check the accuracy of the results and there is considerable flexibility in the type of measurement that can be made.