Adjustable waveform spark source

Abstract

A capacitor is charged to a high voltage, and then is discharged through a circuit comprising an analytical spark gap and first and second inductive elements, whereby the discharge current is oscillatory. The waveform of the discharge current is modified by a diode rectifier shunted across the series combination of the analytical spark gap and the second inductive element. To provide for adjustment of the waveform over a wide range, the second inductive element is adjustable in inductance. The first inductive element is also preferably adjustable in inductance. Provision may also be made for changing the capacitance of the capacitor. A reversing switch makes it possible to reverse the polarity of the diode rectifier. One or more control spark gaps may be connected in series with the analytical spark gap. An electronic switching device may be connected across one of the control spark gaps to initiate the discharge of the capacitor. Either or both of the inductive elements may be replaced with other reactances or impedances, such as transmission lines. Coupling may be provided between the inductive elements. Inductance or impedance may be provided in the diode circuit. The capacitor may be replaced with some other source of alternating current or pulses. The spark may be ignited by high voltage, developed at a radio frequency by a quarter wave line. The diode rectifier may be replaced with a silicon controlled rectifier, silicon controlled switch, or some other active element.

I claim: 
     
       1. A spark .Iadd.type light .Iaddend.source .Iadd.for producing light for spectroscopic analysis, .Iaddend.comprising .[.a.]. .Iadd.an analytical .Iaddend.spark gap,   a storage capacitor   means for causing said capacitor to be discharged across said spark gap,   first and second .[.reactive elements.]. .Iadd.inductive devices .Iaddend.connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second .[.reactive element.]. .Iadd.inductive device .Iaddend.to modify the waveform of the discharge current across said spark gap. .[.2. A spark source according to claim 1, in which said first reactive element is predominantly inductive..]. .[.3. A spark source according to claim 1,   
     
     
       in which said second reactive element is predominantly inductive..]. 4. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said first reactive element .[.includes.]. .Iadd.including .Iaddend.an   
     
     
        inductance coil. 5. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said second reactive element .[.includes.]. .Iadd.including .Iaddend.an   
     
     
        inductance coil. 6. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said first reactive element .[.is.]. .Iadd.being .Iaddend.adjustable in   
     
     
        inductive reactance. 7. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said second reactive element .[.is.]. .Iadd.being .Iaddend.adjustable in   
     
     
        inductive reactance. 8. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap,   said first and second reactive elements .[.are.]. .Iadd.being .Iaddend.adjustable in inductive reactance to provide for adjustment of   
     
     
        the waveform. 9. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said first reactive element .[.comprises.]. .Iadd.comprising .Iaddend.a   
     
     
        transmission line. 10. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said second reactive element .[.comprises.]. .Iadd.comprising .Iaddend.a   
     
     
        transmission line. 11. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said first and second reactive elements .[.comprise.]. .Iadd.comprising   
     
     
        .Iaddend.first and second portions of the same inductance coil. 12. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said first and second reactive elements .[.are.]. .Iadd.being   
     
     
        .Iaddend.constructed and arranged to produce coupling therebetween. 13. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said first and second reactive elements .[.comprise.]. .Iadd.comprising   
     
     
        .Iaddend.respective first and second coupled inductance elements. 14. A spark .Iadd.type light .Iaddend.source according to claim 1, in which said rectifier is polarized in a direction opposite from the   
     
     
        initial surge of discharge current across said spark gap. 15. A spark .Iadd.type light .Iaddend.source according to claim 1, including means for selectively reversing the polarization of said   
     
     
        rectifier. 16. A spark .Iadd.type light .Iaddend.source according to claim 1, including a reversing switch for selectively connecting said rectifier to   
     
     
        be conductive in either direction. 17. .[.A spark source according to claim 1, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   a storage capacitor,   means for causing said capacitor to be discharged across said spark gap,   first and second reactive elements connected between said capacitor and said spark gap to carry the discharge current,   and a rectifier shunted across said spark gap and said second reactive element to modify the waveform of the discharge current across said spark gap, .Iaddend.   said second reactive element .[.is.]. .Iadd.being .Iaddend.adjustable in inductive reactance,   said rectifier being polarized in a direction opposite to the initial surge   
     
     
        of the discharge current across said spark gap. 18. A spark .Iadd.type light .Iaddend.source according to claim 1, including at least one additional spark gap in series with said first   
     
     
        mentioned spark gap. 19. A spark .Iadd.type light .Iaddend.source according to claim 1, including a control spark gap connected in series with said first mentioned spark gap,   and electronic switching means connected across said control spark gap for   
     
     
        initiating the discharge of said capacitor. 20. A spark .Iadd.type light .Iaddend.source according to claim 19, in which said electronic switching means comprise a controllable arc   
     
     
        discharge tube. 21. A spark .Iadd.type light .Iaddend.source according to claim 1, including a plurality of control spark gaps connected in series with said first mentioned spark gap,   and electronic switching means connected across one of said control spark   
     
     
        gaps for initiating the discharge of said capacitor. 22. A spark .Iadd.type light .Iaddend.source according to claim 1, in which said capacitor, said spark gap and said first and second .[.reactive elements.]. .Iadd.inductive devices .Iaddend.are included in a series oscillatory circuit to produce an oscillatory discharge current   
     
     
        across said spark gap. 23. A spark .Iadd.type light .Iaddend.source according to claim 1, in which said rectifier is shunted across the series combination of said spark gap and said second .[.reactive element.]. .Iadd.inductive device.   
     
     
        .Iaddend. 24. A spark .Iadd.type light .Iaddend.source according to claim 1, 
     
     
       in which said rectifier comprises a controlled rectifier. 25. A spark .Iadd.type light .Iaddend.source according to claim 1, in which said means comprises switching means in circuit with said spark   
     
     
        gap. 26. A spark .Iadd.type light .Iaddend.source according to claim 1, in which said means comprises electronic switching means in circuit with   
     
     
        said spark gap. 27. A spark .Iadd.type light .Iaddend.source .Iadd.for producing light for spectroscopic analysis.Iaddend., comprising .[.a.]. .Iadd.an analytical .Iaddend.spark gap,   an impedance connected to said spark gap,   said impedance comprising .[.reactive means.]. .Iadd.an inductive device.Iaddend.,   means including an alternating current source for producing a discharge current through said impedance and across said gap,   and an active circuit element connected in shunt with said impedance and said spark gap for modifying the waveform of the discharge current across said gap,   said active element being constructed and arranged to be conductive during   
     
     
        a portion of the altrnating current from said source. 28. A spark .Iadd.type light .Iaddend.source according to claim 27, 
     
     
       in which said active element comprises a rectifier. 29. A spark .Iadd.type light .Iaddend.source according to claim 27, 
     
     
       in which said active element comprises a silicon controlled rectifier. 30. A spark .Iadd.type light .Iaddend.source according to claim 27, 
     
     
       in which said active element comprises a silicon controlled switch. 31. A spark .Iadd.type light .Iaddend.source according to claim 27, 
     
     
       in which said active element comprises a Triac. 32. A spark .Iadd.type light .Iaddend.source according to claim 27, 
     
     
       in which said active element comprises an electron discharge tube. 33. A spark .Iadd.type light .Iaddend.source according to claim 27, in which said source includes a storage capacitor and means for charging said capacitor,   said capacitor being discharged through said impedance and across said gap to produce said discharge current. .[.34. A spark source according to claim 27,   
     
     
       in which said reactive means comprises an inductive element..]. 35. .[.A spark source according to claim 27, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   an impedance connected to said spark gap,   said impedance comprising reactive means,   means including an alternating current source for producing a discharge current through said impedance and across said gap,   and an active circuit element connected in shunt with said impedance and said spark gap for modifying the waveform of the discharge current across said gap,   said active element being constructed and arranged to be conductive during a portion of the alternating current from said source, .Iaddend.   said reactive means .[.comprises.]. .Iadd.comprising .Iaddend.an inductance   
     
     
        coil. 36. .[.A spark source according to claim 27, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   an impedance connected to said spark gap,   said impedance comprising reactive means,   means including an alternating current source for producing a discharge current through said impedance and across said gap,   and an active circuit element connected in shunt with said impedance and said spark gap for modifying the waveform of the discharge current across said gap,   said active element being constructed and arranged to be conductive during a portion of the alternating current from said source, .Iaddend.   said reactive means .[.comprises.]. .Iadd.comprising .Iaddend.an adjustable   
     
     
        inductance coil. 37. .[.A spark source according to claim 27, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising a spark gap,   an impedance connected to said spark gap,   said impedance comprising reactive means,   means including an alternating current source for producing a discharge current through said impedance and across said gap,   and an active circuit element connected in shunt with said impedance and said spark gap for modifying the waveform of the discharge current across said gap,   said active element being constructed and arranged to be conductive during a portion of the alternating current from said source, .Iaddend.   said reactive means .[.comprises.]. .Iadd.comprising .Iaddend.a   
     
     
        transmission line. 38. .[.A spark source according to claim 27, in which.]. .Iadd.A spark type light source for producing light for spectroscopic analysis, comprising a spark gap,   an impedance connected to said spark gap,   said impedance comprising reactive means,   means including an alternating current source for producing a discharge current through said impedance and across said gap,   and an active circuit element connected in shunt with said impedance and said spark gap for modifying the waveform of the discharge current across said gap,   said active element being constructed and arranged to be conductive during a portion of the alternating current from said source, .Iaddend.   said reactive means .[.comprises.]. .Iadd.comprising .Iaddend.a coaxial   
     
     
        cable. 39. A spark .Iadd.type light .Iaddend.source according to claim 27, including switching means in series with said spark gap for initiating the   
     
     
        discharge current across said spark gap. 40. A spark .Iadd.type light .Iaddend.source according to claim 27, including electronic switching means in series with said spark gap for   
     
     
        initiating the discharge current across said spark gap. 41. A spark .Iadd.type light .Iaddend.source according to claim 27, including means for breaking down said spark gap to initiate the discharge   
     
     
        current across said gap. 42. A spark .Iadd.type light .Iaddend.source according to claim 27, including means for ionizing said spark gap to initiate the discharge   
     
     
        current across said gap. 43. A spark .Iadd.type light .Iaddend.source according to claim 27, including a high voltage radio-frequency source connected to said spark for breaking down said spark gap to initiate the discharge current across said   
     
     
        gap. 44. A spark .Iadd.type light .Iaddend.source according to claim .[.27.]. .Iadd.35.Iaddend., .[.in which said reactive means comprises inductive means,.]. .Iadd.in which .Iaddend.said active circuit element .[.comprising.]. .Iadd.comprises .Iaddend.a rectifier. .[.45. A spark source according to claim 27, in which said impedance comprises a silicon controlled rectifier..]. .[.46. A spark source according to claim 27,   
     
     
       in which said impedance comprises a solid state switching device..]. 47. A spark .Iadd.type light .Iaddend.source according to claim 27, in which said active circuit element comprises a rectifier,   said impedance comprising an inductance coil. .[.48. A spark source according to claim 27,   in which said active circuit element comprises an adjustable inductance coil..]. .[.49. A spark source according to claim 27,   
     
     
       in which said active circuit element comprises a transmission line..]. 50. A spark .Iadd.type light .Iaddend.source accoding to claim 27, in which said source includes a storage capacitor which is adjustable in   
     
     
        capacitance. 51. A spark .Iadd.type light .Iaddend.source according to claim 27, in which said active circuit element comprises a rectifier which is polarized in a direction opposite to the initial surge of the discharge current. .[.52. A method of producing radiation for spectral analysis,   comprising the production of an electrical spark discharge having an oscillatory electrical spark current waveform,   said spark discharge being produced in the presence of a material to be analyzed,   causing said waveform to have alternate first and second repetitive half-cycles in which said first half-cycle in each case has a spark current of a sufficiently great peak magnitude to produce intense vaporization of said material,   and in which said second half-cycle in each case has a spark current of a substantially smaller magnitude than the previously-mentioned magnitude for producing a superior spectrum for analytical purposes..]. .[.53. A method according to claim 52,   including the utilization of time-resolved spectroscopy to produce time-resolved spectra of the radiation derived from said second repetitive   
     
     
        half-cycles..]. .Iadd.54.  A spark type light source for producing light for spectroscopic analysis, comprising an analytical spark gap,   an impedance connected to said spark gap,   said impedance comprising an inductive device,   means including an alternating current source for producing a discharge current through said impedance and across said gap,   and an active circuit element connected in shunt with said impedance and said spark gap for modifying the waveform of the discharge current across said gap,   said active element being constructed and arranged to be conductive during a portion of the alternating current from said source,   said active element comprising a rectifier,   said source including a storage capacitor and means for charging said capacitor,   said capacitor being discharged through said impedance and across said gap   
     
     
        to produce said discharge current. .Iaddend. .Iadd.55.  A spark type light source, for producing light for spectroscopic analysis, comprising an analytical spark gap,   an impedance connected to said spark gap,   said impedance comprising an inductance coil,   means including an alternating current source for producing a discharge current through said impedance and across said gap,   and an active circuit element connected in shunt with said impedance and said spark gap for modifying the waveform of the discharge current across said gap,   said active element being constructed and arranged to be conductive during a portion of the alternating current from said source,   said active element comprising a rectifier,   said source including a storage capacitor and means for charging said capacitor,   said capacitor being discharged through said impedance and across said gap to produce said discharge current. .Iaddend.