Showing papers on "Spark (mathematics) published in 1985"

A laser-triggered spark gap model

Abstract: Laser preionization is a method whereby the formative lag time and jitter of spark gaps can be reduced, and breakdown can be initiated at voltages significantly below the self‐breakdown value. In the spark gaps of interest (100‐ns spark duration), the plasma column expands from an initial laser preionized diameter of approximately 50 μm to an arc of diameter in excess of 1 mm, and conducts greater than 12‐kA peak current. Since the time required for the resistive collapse of the plasma is comparable to the spark duration, the spark gap represents a non‐negligible resistive loss in the circuit. The objective of this study is to understand the basic mechanisms by which laser‐triggered spark gaps develop and to provide a basis to optimize their design and minimize their resistive losses. To study the expansion and conduction phases of laser‐triggered spark gaps, a first principles model has been developed. This model includes gas dynamics, electron collision kinetics, radiation transport, and external circuitry in a self‐consistent formulation. The formulation of the model is discussed and results are compared to experimental data. We find that growth of the spark column is dominated by gas dynamic expansion of the hot ionized core, augmented by photoionization and thermal ionization at the plasma column boundary. The plasma column is confined within a high‐density cylindrical shell of neutral gas that traps ionizing radiation in a region of low E/N (electric field divided by gas density), thereby inhibiting expansion by nonhydrodynamic means (electron avalanche).

Investigation on ignition ability of composite sparks in flowing mixtures

Abstract: In order to clarify the mechanism of the ignition process of flowing gases by composite sparks and to pursue important factors influencing the process, the effects of the behavior of spark discharge path, spark duration, electrode size, discharge type and multiple spark on the minimum ignition energy were investigated by using a long-duration spark generator which can independently vary the spark duration and the discharge power. The results indicate that the behavior of the blown spark path in the flowing gaseous mixture is closely related to the ignition ability of the spark, and that the optimum spark duration for glow discharge does not appear clearly under flowing conditions. The effect of spark electrodes is suggested to be due to a loss of heat or radical species and a quenching of flame kernels by wake turbulence induced by the spark electrodes. Moreover, it is suggested that the multiple spark, appearing for long duration sparks under flowing conditions, considerably enhances the ignition ability due to its repetition effect.

Stabilized Combustion in a Spark Ignited Engine through a Long Spark Duration

Abstract: An investigation has been done on the relationship between spark ignition characteristics and combustion stability in a gasoline engine The spark discharge parameters examined are the spark current, energy, and duration It is found that lengthening the spark discharge duration is particularly effective in achieving stabilized combustion The analytical results of a constant volume combustion chamber test verify that a longer spark duration promotes flame initiation and makes reliable flame propagation possible The length of the spark duration is regarded as the period from ignition to the onset of combustion pressure rise The spark duration must be longer than the heat release delay The reason is that a long-duration spark shortens the initial combustion period, thereby making it possible to reduce the fluctuations that occur during that period This is particularly important because such fluctuations are known to be the main cause of the cycle-to-cycle fluctuations in engine combustion The spark duration should be three to four times longer than the conventional spark discharge

Spark spectroscopic high-pressure gas analyzer

Abstract: A spark spectroscopic high-pressure gas analyzer including a spark chamber, having a pair of electrodes, for receiving a sample of the pressurized gas to be analyzed. A voltage is provided across the electrodes for generating a spark in the pressurized gas sample. A selected wavelength band of radiation emitted from the spark discharge in the pressurized gas corresponding to a component to be sensed in the gas is detected. The intensity of the emission in the wavelength band is integrated during the afterglow time interval of the spark emission and a signal representative of the integrated intensity of the emission in the selected narrow wavelength band is employed to determine the proportion of the component in the gas.

Formation of a continuous laser spark in air

Abstract: A study was made of the growth of a laser spark created by focusing a giant laser pulse with an axicon. A spark appeared after 20–50 nsec, depending on its nature, and the radiation emitted by the spark plasma lasted for more than 100 μsec. The maximum diameter of the luminous region was 1 cm. The longitudinal and transverse spark expansion velocities were determined. Measurements were made using a laser-triggered image-converter camera which was specially designed for this purpose.

Electronic ignition system

Abstract: An electronic ignition system for a reciprocal piston, spark ignition internal combustion engine includes sensors which generate output signals representative of the rotational position and speed of the engine output shaft. A computer responsive to the sensor inputs generates an output signal which electrically connects a source of electrical energy to the primary coil of an ignition transformer for a predetermined period of time prior to the desired energization of the spark plug regardless of the rotational speed of the engine output shaft, but dependent on the voltage of the source of electrical energy. Initiation of the predetermined period is dependent on a manually set spark advance.

Interactive spark and throttle idle speed control

Abstract: A method for controlling the idling speed of an internal combustion engine includes generating a constant time delay to determine the delay from the occurrence of top dead center until the next spark plug firing. A speed error signal is applied to the parallel combination of a phase compensator and an integrator to generate a signal for controlling airflow through the throttle of the internal combustion engine.

Low‐inductance capacitive probe for spark gap voltage measurements

Abstract: A novel high‐voltage (>50 kV) capacitive probe has been developed to measure the voltage drop across a laser‐triggered spark gap. The capacitors which comprise the voltage probe consist of three flat, annular rings that are housed within the spark gap chamber. The rings are oriented perpendicular to the spark column axis such that the column is formed in the open center of the rings. Polyethylene and Kapton foil are employed as dielectrics. The resistive portion of the divider is housed in a shielded enclosure external to the switch chamber. The inherent simplicity of the probe design ensures low inductance while minimizing stray capacitance; thus, the probe has excellent response characteristics (≊1‐ns theoretical rise time), and does not interfere with the performance of the switch. The probe has also been designed to permit access for laser triggering and interferometric measurements of the spark column formation. The voltage, current, and resistance characteristics of a laser‐triggered spark gap for various gas mixtures are also discussed.

Air-forced injection system for spark ignition engines

Abstract: Systeme d'injection de carburant utilisant de l'air comprime pour un moteur a allumage par etincelle

X-ray diagnostics of hot dense plasma in low-inductance vacuum spark

Abstract: X-ray spectroscopic diagnostics are used to study the hot dense plasma of a micropinch (MP) in a low inductance vacuum spark.

Investigation of electrical properties of a 120 cm PSC using an inner spark pulser

Abstract: Characteristics of fast pulse propagation in a large planar spark counter (PSC) are simulated using a pulser located inside the spark gap. Besides the main mode of pulse propagation, three undesirable modes are observed. These latter strongly distort the shape of the pulse. Characteristics of these modes and methods to eliminate their effects are demonstrated. We present an electrical design for a 120 cm spark counter along with some of its electrical properties as revealed by measurements made with the inner spark pulser. In the present counter design the charge of a pulse is shared by several neighboring strips, enabling one to measure the transverse position of a spark to a high degree of accuracy.

Spark detecting device in current collector

Abstract: PURPOSE:To prevent an erroneous discrimination due to an external noise by providing the second detector in addition to the first detector, and judging that a spark is generated when detection signals are obtained simultaneously from these detectors. CONSTITUTION:When a spark is generated between a current collecting ring and a brush 3, this spark noise is detected by an antenna type spark detector of the first spark detector. On the other hand, since the current of the brush which generates the spark is pulsated or intermittently continued, the detection current in response to the variation in the current is obtained from the current detector 20 of the brush. Further, the detected current in response to the variation in the current share is obtained from the detector 20 of other brush by the pulsation of the current of the brush which generates the spark. Thus, when the detection signals are simultaneously obtained from the first and second detectors, an AND circuit 17 operates to detect the spark.

Analysis of parameters in spark ignition of flowing mixtures.

Abstract: 放電時間を電力と独立に変えることのできる後続成分を有する合成水花によって層流プロパン-空気希薄混合気の点火実験を行った.まず,流動混合気中で吹き流される火花径路の時間的推移と,火花径路と火炎核の相対的位置とを明らかにした.つぎに,流動混合気のグロー放電による最小点火エネルギは放電時間を変えてもほぼ一定であること,アーク放電がグロー放電よりも高い点火能力をもつこと,電極形状の影響等が明らかにされた.

Method of controlling ignition timing and device therefor

Abstract: PURPOSE:To enhance fuel economy and drivability, by providing judging means for judging where the present place is a level land or a highland and a compensating means for compensating the spark advance of an engine if it is a highland CONSTITUTION:Upon operation other than idle operation, a basic spark advance THB is obtained in accordance with a rotational speed NE and an intake-air pipe pressure PM at the step P26 When the intake-air pipe pressure PMA is 650 mmHg, a value in a memory area A is added with 5 at the step P32, and is then stored A compensation computing process is carried out in accordance with the operating condition of the engine at the step P28 to obtain a final spark advance THF With this arrangement, a desired spark advance may be obtained irrespective of a level land or a highland, and therefore, fuel economy and drivablility may be enhanced

Simultaneous Laser Preionization of Dual Spark Columns in a High Voltage Switch

Abstract: : The preliminary investigation of simultaneous laser triggering (lambda = 248 nm) of a spark gap (50 kV, 18 kA, 100 nsec) switch with two parallel preionized columns ( separation 1. 3 mm) is reported. Interferograms of the expanding arc channels are obtained with a laser interferometer having a time and spatial resolution of 5 ns and 10 micro m, respectively. Comparison of the dual spark column voltage and current characteristics are made to those of a single channel spark column.

An experimental study on knock-intensity in spark-ignition engines.

Abstract: 火花点火可能な急速圧縮機によってノックを再現し,得られた指圧線図から求めた圧力振動振幅によってノック強さを定義した.このノック強さに影響する重要な要因として火炎伝ばによる燃焼質量割合が存在すること,また圧縮比,当量比の影響などを明らかにした.円筒形燃焼室においてノック強さが大きく変動するのは,ガス振動モードの節線位置が試行ごとに変化するためであることが2種の実験手法によって確認された.

Ignition timing control device for internal-combustion engine

Abstract: PURPOSE:To improve the noise resistance by generating a control signal for the maximum/minimum spark advance position through a hysteretic rectangular wave shaping circuit by means of rotating a rotor which has angular information data contrary to each other at intervals corresponding to the spark advance width. CONSTITUTION:The signal of a sensor 2, which comes from the rotation of a magnetic rotor 20 with a protrusion 21 corresponding to the spark advance width, is level-converted at a constant voltage Vr, which is made as a set signal through a comparator 103 and an inverter 104. Through a hysteretic rectangular wave shaping circuit 30, it is shaped into rectangular pulses at intervals of an angular space corresponding to the spark advance width, and further, through an integrating circuit 40, it is converted into operational waves with the prescribed inclination which is reset once per rotation of the rotor. And a point where it intersects the threshold value Vth of a comparator 112 is the ignition point, generating an ignition signal J. In this way, a signal sensor can detect the maximum/minimum spark advance position, and the noise resistance can be considarably improved by the hysteretic action.