Staircase Waveform Research Articles

A Cockcroft-Walton for FELTRON: the new mu -wave source for TeV colliders

A pulsed powerful Cockcroft-Walton generator for an electrostatic accelerator is presented. The electrostatic accelerator is designed to provide a pulsed electron beam of 5.5 MeV, 100 A, and 0.5 mu s with a repetition rate of 1 kHz. The output voltage has a descending staircase waveform. This voltage provides an electron beam made up of ten sections having different energies. Two adjacent pieces have a relative energy variation Delta gamma ij/ gamma of 1%. A dispersive system spatially separates those sections into ten 50-ns-long electron beam pulses. >

Multiple square wave voltammetry: experimental verification of the theory

The experimental verification of a new multi-impulse electroanalytical method, multiple square wave voltammetry (MSWV), in which several impulses of constant amplitude are superimposed on each step of a staircase waveform is presented. In particular, it has been confirmed that the voltammograms, obtained from current or charge measurements at a SMDE using the reversible couple Fe(II)/Fe(III) in oxalate medium, can be adequately interpreted in a very simple way. The analysis of experimental data still remains valid when a large number of impulses are applied to each step of the potential staircase. This yields a considerable improvement in real sensitivity at low concentrations.

Trace analyses of impurities in povidone by square-wave voltammetry

Povidone (polyvinylpyrrolidone) is a water soluble polymer used in a variety of pharmaceutical, beverage, cosmetic, and agricultural applications. The free radical-induced polymerization of vinylpyrrolidone using aqueous hydrogen peroxide/ammonia as an initiator allows for rapid, easily controlled reactions. However, the reactivity of the various components can give rise to trace levels of undesirable by-products. The analytical methods available for these impurities utilize dissimilar procedures with time consuming sample preparation steps; and the need for high product quality requires methods with low detection limits for which many of the established procedures are not suitable. A general approach for the analysis of impurities in our laboratory has involved the use of square wave voltammetry (SWV) for the quantitation of electroactive species. This technique couples the ability to determine species at very low levels (sub ppm) with analysis speed, making it ideal for aiding in process optimization. The version of square wave voltammetry used in our laboratory was developed by Osteryoung [1] and first commercialized by Bioanalytical Systems. In the technique, a pulse train of square waves is superimposed on a staircase wave form. A single square wave cycle (forward and reverse pulse) is generated per staircase step. Current is sampled near the end of each forward and reverse pulse. The difference in currents generated from the forward/reverse signals yields the analytical current response. The very nature of the experiment results in the following advantages: a) Scan rate, which is dependent primarily on square wave frequency, is fast. A typical experiment covering a potential range of I V may take only 5 seconds by SWV compared to 3 minutes by other pulse voltammetric techniques. b) For reversible systems, enhanced peak currents are obtained as the net current is the difference between a positive forward current and a reverse current which is opposite in sign. c) As a pulse technique, discrimination against charging current improves the detection limit. d) Multiple scanning is used with signal averaging to improve the signal-to-noise ratio. e) Diagnostic information can be obtained (as in cyclic voltammetry) by observing the individual forward and reverse currents.

Theory of multiple square wave voltammetries

A study of square wave voltammetries in which several pairs of opposing impulses are superimposed on each step of a staircase waveform, with or without integration of the current, is presented for reversible redox systems. The new fast techniques that result, yield responses greater than those obtained with the other classical methods. This work shows that the experimental results, for any square wave voltammetry, can be adequately interpreted using an extremely simple mathematical formula.

Ultrafast voltage pulse shaping for streak and framing camera deflection

The generation of voltage waveforms with ultrafast risetime using a single semiconductor switch is demonstrated with direct application in streak and framing camera deflection. Voltage ramps, square, triangular and staircase waveforms are obtained by combining at the load the electrical signal of a number of output lines.

Minicomputer-controlled, background-subtracted anodic stripping voltammetry: evaluation of parameters and performance

A new minicomputer-controlled anodic stripping voltammetry technique is described. The technique uses differential voltammetry at one electrode, and uses a rapid data-averaging algorithm to avoid the need for scan averaging; this allows excellent sensitivities and short analysis times, with adequate reproducibilities. Both linear-scan and staircase waveforms are discussed in conjunction with the technique, and the approximate Roe—Toni theory for linear-scan voltammetry is shown to apply. The system response is investigated for film thickness, scan rate, deposition time, electrode rotation rate, and metal concentration. Results were used to optimize the sensitivity of the technique. The metal ions Cd, Pb and Cu could be determined in solutions as dilute as 1–10 pg/ml -1 in 15 min. The viability of the technique in solutions showing a large background is also discussed, and a comparison is made with scan-averaged techniques.

Pulsed voltammetric stripping at the thin-film mercury electrode

A computer-controlled data acquisition system was used to generate comparative data for thin-film anodic stripping voltammetry with staircase, differential pulse and squarewave waveforms. Each waveform was tested for its sensitivity and speed of analysis. The square-wave form is the most sensitive, whether square wave or differential pulse measurements are used. This waveform offers the advantages of fast analysis time and discrimination against charging currents.

Staircase voltammetric stripping analysis at thin film mercury electrodes

Abstract : Anodic stripping voltammetry (ASV) is a powerful analytical tool for trace metal analysis. In this paper, an experimental study of the staircase ASV is presented. The various parameters governing the stripping current were studied and analytical applications for the determination of low level trace metals were demonstrated. Anodic stripping voltammetry from a rotating thin film mercury electrode has been carried out employing a staircase waveform. Experimental results are shown to be in excellent agreement with previously developed theory. The method is of the same order of sensitivity as differential pulse stripping, but is much faster to perform. Reproducibility is better than 1% on the same film and 5% on replated films at the 10 ppb level.

Cardiopulmonary baroreflexes: effects of staircase, ramp, and square-wave stimulation.

Anesthetized dogs were pump perfused in a system that held systemic arterial pressure constant. Pulmonary arterial beds were pressurized, and the induced transient falls of systemic vascular resistance (SVR) were measured. An approximately linear relationship between percent fall of SVR and pulmonary artery pressure was obtained. Left atria and pulmonary venous beds were pressurized using square-pulse, staircase, and ramp wave forms, and changes in SVR were measured. The effect of varying the interval between stimuli was appraised. An approximately linear relationship was obtained for responses to square-wave left atrial forcing pressure (Pla). With staircase forcing, the change of SVR per unit change of Pla depended upon prestimulus Pla. With ramp forcing, responses increased approximately linearly with respect to the logarithm of the rate of pressure rise. Responses to square-wave stimulation varied directly with respect to the interstimulus interval. This study shows that left atrial-pulmonary vein baroreflexes are capable of producing substantial short-term falls of SVR, and that the response depends upon stimulus pressure, rate of pressure change, base-line pressure, and pressure history.

The transmission of digital information across potential barriers: application to the direct scanning and recording of mass spectrometric ionization efficiency curves

A method is described whereby voltages floating at several kilovolts above ground may be measured and transferred digitally to ground potential for input to a computer or chart recorder. The system, which also contains a facility for generating a staircase waveform at high potentials has been employed for the direct plotting of mass spectrometric ionization efficiency data.

A New Sample Interpolator of Linear Type

A new data processor is presented giving a precise approximation to linear interpolation. The processor produces a staircase waveform with a constant and high number of steps connecting two consecutive samples. The implementation of the interpolator is described and some test results are given.

Multiple Frame Image Converter Unit with up to Seven Frames per Trigger Using Solid State Design

Driving the RCA 4449A/C73435Q electrostatically focused image converter tube, the unit provides seven screen pictures of 25 mm height and 8 mm width in time intervals of 1–110 μsec and with 0.1–10 μsec exposures. The solid state circuitry generates +275 V p-p shutter pulses with 25 nsec risetime and a correctly timed balanced staircase waveform of 2400 V p-p.

Counter-Decoder Staircase Generator†

ABSTRACT A staircase waveform generating circuit that provides a good performance is described. Such waveforms have wide applications. The present circuit employs a simple arrangement comprised of parallel counter stages, a. diode matrix and a diode OR gate. The adjustment of the circuit is also simple and the accuracy of the waveform obtained depends primarily on good tolerance of a few resistors only.

A Transistor Staircase Waveform Generator and its Application as a Storage Counter†

ABSTRACT A linear straircase generator employing a transistor blocking oscillator is described. An application, of the device to storage counting in which the counting ratio can be varied smoothly and in a continuous fashion is discussed. Expressions for the counting ratio are also derived.

Trochotron high-speed beam switching tubes

The trochotron high-speed beam switching tube is described and the characteristics discussed. Expressions for the maximum discrimination and maximum continuous counting rates are derived. Binary, single pulse and sine wave drive circuits are discussed. Methods of extending the number of output channels and of generating staircase or analogue waveforms are illustrated. Details are given of remote digitron read-out, and mention made of a method of modulation.

Apparatus for the measurement of non-linearity in television trunk systems

The paper describes the normal methods of measuring non-linearity, using sawtooth and staircase waveforms, and it outlines their short-comings. Two systems that overcome these difficulties are described, and their uses are compared with particular reference to television-type waveforms (containing a d.c. component).Reference is made to that particular form of non-linearity in which the ratio of the synchronizing-signal amplitude to that of the picture signal is altered by the transmission system.