Glow discharge lamp

Patent metadata

Field	Value
Publication number	US-9485848-B2
Application number	US-201314413820-A
Country	US
Kind code	B2
Filing date	Jul 10, 2013
Priority date	Jul 11, 2012
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

The disclosure includes a glow-discharge lamp including: an elongate casing transparent to illuminating radiation and containing a plasma gas; a device for applying an electric field for maintaining a plasma in the so-called positive column region of the casing, the device including two electrodes forming an anode and a cathode located in the casing at each end thereof; and a radio-frequency or microwave cathode plasma source arranged in the casing in relation to the cathode-forming electrode, such as to generate a high-frequency discharge located on the surface of the electrode in order to generate the plasma. The disclosure also includes a lighting method of such a glow-discharge lamp.

First claim

The invention claimed is:

1. A glow discharge lamp comprising:
an elongated envelope, transparent to lighting radiation and containing a plasma gas;
a device for applying an electric field suitable for maintaining a plasma in a region of the envelope called a positive column, including two electrodes constituting an anode and a cathode situated in the envelope, at each end of the envelope; and
a microwave or radio-frequency cathode plasma source positioned in the envelope relative to the electrode constituting the cathode so as to generate a localized high-frequency discharge on the surface of the electrode to generate the plasma.

2. The lamp of claim 1 , which is supplied with a periodic voltage at 50 Hz or 60 Hz, the lamp further comprising two cathode plasma sources situated in the envelope relative to each of the two electrodes so as to generate a localized radio-frequency or microwave plasma at the surface of each of the electrodes.

3. The lamp of claim 1 , wherein the cathode plasma source is an inductive radio-frequency source.

4. The lamp of claim 1 , wherein the cathode plasma source is a microwave source.

5. The lamp of claim 1 , wherein a pressure inside the envelope is less than 10 torr (1330 Pa).

6. The lamp of claim 5 , wherein the cathode plasma source is an inductive radio-frequency source and the lamp further includes a device for applying a static axial magnetic field at the plasma source.

7. The lamp of claim 5 , wherein the cathode plasma source is a microwave source and the lamp further includes a device for applying a static magnetic field with intensity equal to an electron cyclotron resonance intensity at the plasma source.

8. The lamp of claim 6 , further comprising a device for applying, at the cathode, a static axial magnetic field with its intensity decreasing from the cathode toward the positive column.

9. The lamp of claim 6 , further comprising a device for applying a static axial magnetic field along the positive column.

10. The lamp of claim 9 , wherein the device for applying a static axial magnetic field is a solenoid wound around the envelope.

11. The lamp of claim 1 , wherein the envelope takes the form of a straight tube.

12. The lamp of claim 1 , wherein the envelope takes the form of a tube wound in a spiral.

13. A lighting method using a glow discharge lamp, the lamp comprising an elongated envelope transparent to lighting radiation and containing a plasma gas ( 2 ), and two electrodes constituting an anode and a cathode, situated inside the envelope, at each end of the envelope, the method comprising:
generating a microwave or radio-frequency cathode plasma by a localized high-frequency discharge at the surface of the electrode constituting the cathode, the discharge being created by a microwave or radio-frequency cathode plasma source positioned in the envelope; and
applying, between the anode and the cathode, a voltage suited for applying an axial electric field for maintaining the plasma in a region of the envelope called a positive column.

14. The method of claim 13 , wherein the voltage applied is an AC voltage at 50 or 60 Hz and the cathode plasma is generated alternately at the surface of one and the other electrode, to with the electrode constituting the cathode depending on the polarity of the voltage applied.

15. The method of claim 13 , wherein a static axial magnetic field, with its intensity decreasing from the cathode toward the positive column, is further applied at the cathode at the surface whereof the cathode plasma is generated.

16. The method of claim 13 , wherein a static axial magnetic field is further applied along the positive column.

17. The method of claim 13 , wherein the cathode plasma is generated at a frequency comprised between 1 MHz and 100 MHz.

18. The method of claim 17 , wherein a static axial magnetic field is further applied at the cathode, at the surface whereof the cathode plasma is generated, so as to obtain coupling in a helical mode.

19. The method of claim 13 , wherein the cathode plasma is generated at a frequency comprised between 100 MHz and 5.8 GHz.

20. The method of claim 19 , wherein a static magnetic field with an intensity equal to an electron cyclotron resonance intensity is further applied at the cathode at the surface whereof the cathode plasma is generated, so as to obtain electron cyclotron resonance coupling.

21. The method of claim 13 , wherein a pressure in the envelope is less than 10 torr (1330 Pa).

22. The method of claim 13 , wherein the voltage applied between the electrodes is a DC voltage or an AC voltage at 50 Hz or 60 Hz.

Assignees

• Centre Nat De La Rech Scient (Cnrs)
• Univ Joseph Fourier—Grenoble 1

Inventors

• Lacoste Ana
• Pelletier Jacques

Classifications

• H05H1/48

  using an arc (H05H1/26 takes precedence) · CPC title

• H01J61/327 Primary

  "Compact"-lamps, i.e. lamps having a folded discharge path · CPC title

• H05H1/50

  and using applied magnetic fields, e.g. for focusing or rotating the arc · CPC title

• H05H2001/4652

  Electricity · mapped topic

• H05H1/46 Primary

  using applied electromagnetic fields, e.g. high frequency or microwave energy (H05H1/26 takes precedence) · CPC title