Cathode Unit Research Articles

A Wide-Aperture Metal-Ion Source without Forced Cooling

The design of a small-sized source of metal ions (implanter) for experimental and technological applications is described. Smaller overall dimensions and a significantly simplified design are obtained through the use of an original cathode unit capable of operating without forced cooling.

Multi-cathode cell with flow-through electrodes for the production of iron(ii)-triethanolamine complexes

Nonregenerable reducing agents used in dye houses for the application of indigo, vat dyes and sulfur dyes can be substituted by indirect cathodic reduction techniques. An electrochemical cell for the indirect cathodic reduction of dispersed indigo dyestuff using an alkaline solution of the Fe(iii/ii)-triethanolamine complex as redox mediator was constructed and tested. The cell is built up as divided cell (cathode area 5–10m2, catholyte volume 12L, anolyte volume 1.5L) with several three dimensional cathode units (up to 10) in the same cathode compartment. The cathodes were connected to a common anode and to separately adjustable power supplies. The catholyte was circulated through the porous cathode units parallel to the current direction. Two different electrode materials (copper and stainless steel) and cathode constructions were tested, resulting in an optimized cell construction. The electrochemical cell was characterized by a series of batch electrolysis experiments. Results are given dealing with the cell voltage drop in the cathode, the product yield and the current efficiency at different current densities and cell current. After an optimization step the current efficiency reaches 70–80% at 2 A m–2 current density and 7.8×10–3moldm−3 Fe(ii)-complex. The cell current is 10A.

In Situ Measurements of the Thickness Changes for a Lithium Rechargeable Cell Based on a V 6 O 13 Composite Electrode during Lithium Insertion and Extraction

An in situ technique utilizing a linear voltage displacement transducer device for investigating the thickness changes occurring during the cycling of a lithium insertion type rechargeable cell based on a composite cathode is described. We believe the method is generally applicable to other battery systems which undergo expansion/contraction effects during normal operation. During cell discharge there is a gradual decrease in cell thickness, while the converse is true during the subsequent charging process. The thickness changes are highly reversible over the single cycle considered. The variation of cell thickness was approximately linear with depth of discharge. For the cell in the fully discharged state, the overall thickness change of the active cell components was ∼6%. When the thickness variation associated with the lithium electrode is excluded from the calculations, the cathode increases in thickness during cell discharge and decreases during cell charge. The changes are consistent with the literature‐reported cathode unit cell expansion/contraction effects caused by the lithium insertion/extraction processes.

Characterization of a twin-torch transferred dc arc

The results of a twin-torch transferred de arc .study are presented. The arc system consists of two torches of opposite polarity, and a coupling zone of plasma jets located between them. The torch configuration increases the system reliability and efficiency during material plasma processing. The results of the study present data for the voltage-current characteristics, general behavior of the twin-torch arc, and spatial distribution of the plasma parameters. The plasma parameters have been measured using optical emission spectroscopy for a 200 A (20 k W) do arc, at atmospheric pressure, with argon and nitrogen introduced as plasma forming gases into the anode and the cathode units, respectively. The measurement technique used has allowed the determination of local electron density and temperature values in an inhomogeneous plasma volume having no axial sysmmetry. The data obtained illustrate the novel features of the twin-torch transfrred do arc for its applications in plasma processing.

Directly heated lanthanum hexaboride cathode

A directly heated, cylindrical LaB6 cathode has been tested in a multicusp plasma generator. Magnetic fields generated by the heater and the discharge current are minimized by the special coaxial construction, thus enabling electron emission at very low discharge voltages. At higher discharge voltage, a discharge current greater than 100 A has been obtained from a single cathode unit in a steady-state plasma source operation. When the discharge current exceeds 25 A, the cathode can be operated without any heater current. The emission temperature is maintained just by ion bombardment from the discharge plasma.

Application of lanthanum hexaboride in high-voltage gas-discharge switches

1. A study was made of the possibility of employing cold lanthanum hexaboride cathodes in high-voltage GDD. It is shown that use of LaB6 instead of molybdenum cathodes reduces the pulse-induced voltage drop by a factor of 2–2.5. A particularly low and stable voltage drop is exhibited by devices with cathode units made entirely of LaB6. 2. The variation in structure and chemical composition occurring during operation in the cathode material was studied by the metallographic and electron microprobe methods. Ion bombardment was found to change the composition of the working surface of the cathode. 3. Use of lanthanum hexaboride in cold cathodes of GDD with crossed fields enables devices with substantially improved power characteristics to be obtained, approaching those of pulse hydrogen thyratrons with incandescent cathodes.

535. Cathode unit. (USSR): A G Tabanakov and N A Iofis,USSR Patent No 321868, appl 9 th June 1967, publd 31 st Jan 1972

535. Cathode unit. (USSR): A G Tabanakov and N A Iofis,USSR Patent No 321868, appl 9 th June 1967, publd 31 st Jan 1972

152. Method of preparing a cathode unit with a profiled side surface: Sh I Feoktistova et al,USSR Patent No 316131, appl 7 th April 1970, publd 1 st November 1971

152. Method of preparing a cathode unit with a profiled side surface: Sh I Feoktistova et al,USSR Patent No 316131, appl 7 th April 1970, publd 1 st November 1971

1081. Alloy for making parts of the cathode unit in electronic instruments: E M Savitskii et al, USSR Patent No 304642, appl 14 h Aug 1969, publd 15 th July 1971

Seven types of ion-selective chemical sensors based on poly(vinyl chloride) (PVC) as polymeric membrane, for determination of nitrate ion, have been prepared by using 3-nitro-o-xylene (NOX), tributylphosphate (TBP), bis-(2-ethylhexyl) sebacate (DOS), o-nitrophenyloctyl ether (o-NPOE), tris-2-ethylhexylphosphate (TEHP), dioctylphthalate (DOP) and dibutylphthalate (DBP) as plasticizers and tetradecil ammonium nitrate (TDAN) as ionophore. The response of each electrode was determined in relation to the lipophilicity of the plasticizer used, its rate of exudation to the aqueous phase, polarity, viscosity and its dielectric constant (εr). The experimental data was validated by calibrating the constructed electrodes against a reference Ag/AgCl electrode. The selectivity coefficient (KABPot) of the electrodes was determined by applying the standard mixed solutions method. No correlation between KABPot and εr of the plasticizer was found. ATR-FT-IR technique was used in order to evaluate the life-time of the polymeric membranes ion-selective electrodes (ISEs). The life-time of the electrodes was found to be limited fundamentally by the loss of the sensor and not due to the loss of the plasticizer. All the constructed ISEs showed Nernstian slopes with values of the practical detection limit (PDL) and lower limit of linear response (LLLR) in the range 10−6 to 10−5 mol/dm3. The electrodes constructed by using o-NPOE and/or DBP showed the longest life-time, this being longer than 6 months. The principal interfering anions were found to be ClO3−, BrO3−, Br−, Cl− and Bz− (benzoate). The selectivity loss of the sensors was found to be due to the loss of the ionophore by exudation. No correlation between the calculated values for KABPot of the electrodes and the dielectric constants of the plasticizers was observed.

646. Apparatus for the vacuum treatment of the cathode units of magnetrons: A I Pipko et al, USSR Patent No 277119, appl 27th Dec 1967, publd 29th March 1971

The frequency and amplitude dependences of the dynamic Young's modulus and loss factor of polystyrene (PS) and polyethylene (PE) foams usable for impact sound isolation in floating floors, measured at room temperature, in the frequency range of 100-3000 Hz, and in the range of strain amplitude of 10-5-10-2 respectively, are given in the paper. It is shown that the frame loss factor of the PS and PE foams is low (∼0·01 and ∼0·1, respectively), and that of the foam sheets including air is also low (∼0·1). The frame dynamic Young's modulus of both foams slightly increases with frequency. The dynamic behaviour of the foams is linear up to the strain amplitude of about 10-3, above which the dynamic Young's modulus decreases, whereas the loss factor increases with increasing strain.

647. Method of making cathode units: N A Iofis, USSR Patent No 285118, appl 31st Oct 1968, publd 12th Jan 1971

647. Method of making cathode units: N A Iofis, USSR Patent No 285118, appl 31st Oct 1968, publd 12th Jan 1971

337. A cathode unit: A V Ivlev, USSR Patent, No 247,415, appl 13th Feb 1967, publd 8th Dec 1969

337. A cathode unit: A V Ivlev, USSR Patent, No 247,415, appl 13th Feb 1967, publd 8th Dec 1969