Plasma switch with hollow, thermionic cathode
First Claim
1. A plasma switch comprising:
- an enclosure for containing an ionizable gas;
thermionic hollow cathode means, and anode means, disposed inside the enclosure;
the hollow cathode means axially discharging therefrom an ionized plasma of the gas;
the anode means being disposed to extract electrons from the plasma discharged from the hollow cathode means;
keeper electrode means disposed between the hollow cathode means and the anode means for sustaining plasma discharge of the gas between the hollow cathode means and the keeper electrode means in response to a first voltage applied to the keeper electrode means; and
control electrode means disposed between the keeper electrode means and the anode means for causing the plasma to extend from the hollow cathode means to the anode means in response to a second voltage applied to the control electrode means, the second voltage being positive relative to the cathode means thereby electrically connecting the hollow cathode means and anode means with a low forward voltage drop, the pressure of the ionizable gas being low enough to maintain voltage standoff between the control electrode means and the anode means;
the hollow cathode means, anode means, keeper electrode means, and control electrode means being configured such that the plasma will extend from the hollow cathode means substantially only to the keeper electrode means when the second voltage on the control electrode is changed to be non-positive relative to the cathode means, thereby interrupting the electrical connection between the anode means and the hollow cathode means.
2 Assignments
0 Petitions
Accused Products
Abstract
A hollow cathode capable of self-heating by back ion bombardment to a thermionic emission temperature axially discharges therefrom an ionized plasma of an ambient gas such as xenon. Electrons are axially or radially extractable from the plasma by an anode. A voltage is applied to a keeper electrode disposed between the cathode and anode to sustain plasma discharge of the gas between the cathode and keeper electrode. A control electrode is disposed between the keeper electrode and the anode. Application of a positive voltage (relative to the cathode) to the control electrode causes the plasma discharge to extend from the cathode to the anode, thus closing the switch. Application of a negative control electrode voltage, or simply returning the control electrode to cathode potential, causes the plasma discharge to retract back to the area of the keeper electrode, thereby opening the switch.
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Citations
28 Claims
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1. A plasma switch comprising:
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an enclosure for containing an ionizable gas; thermionic hollow cathode means, and anode means, disposed inside the enclosure; the hollow cathode means axially discharging therefrom an ionized plasma of the gas; the anode means being disposed to extract electrons from the plasma discharged from the hollow cathode means; keeper electrode means disposed between the hollow cathode means and the anode means for sustaining plasma discharge of the gas between the hollow cathode means and the keeper electrode means in response to a first voltage applied to the keeper electrode means; and control electrode means disposed between the keeper electrode means and the anode means for causing the plasma to extend from the hollow cathode means to the anode means in response to a second voltage applied to the control electrode means, the second voltage being positive relative to the cathode means thereby electrically connecting the hollow cathode means and anode means with a low forward voltage drop, the pressure of the ionizable gas being low enough to maintain voltage standoff between the control electrode means and the anode means; the hollow cathode means, anode means, keeper electrode means, and control electrode means being configured such that the plasma will extend from the hollow cathode means substantially only to the keeper electrode means when the second voltage on the control electrode is changed to be non-positive relative to the cathode means, thereby interrupting the electrical connection between the anode means and the hollow cathode means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A plasma switch comprising:
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an enclosure for containing an ionizable gas; hollow cathode means, and anode means, disposed inside the enclosure; the hollow cathode means axially discharging therefrom an ionized plasma of the gas; the anode means being disposed to radially extract electrons from the plasma discharged from the hollow cathode means; keeper electrode means disposed between the hollow cathode means and the anode means for sustaining plasma discharge of the gas between the hollow cathode means and the keeper electrode means in response to a first voltage applied to the keeper electrode means; and control electrode means disposed between the keeper electrode means and the anode means for causing the plasma to extend from the hollow cathode means to the anode means in response to a second voltage applied to the control electrode means, thereby electrically connecting the hollow cathode means and anode means; the hollow cathode means, anode means, keeper electrode means, and control electrode means being configured such that the plasma will extend from the hollow cathode means substantially only to the keeper electrode means when the second voltage on the control electrode is changed to be non-positive relative to the cathode means, thereby interrupting the electrical connection between the anode means and the hollow cathode means. - View Dependent Claims (17, 18, 19, 20)
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21. An inverter/converter, comprising:
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direct current power source means; voltage transformer means having primary winding means connected in circuit with the power source means, and secondary winding means; rectifier means connected in circuit with the secondary winding means; and at least one plasma switch connected in circuit to connect the power source means to the primary winding means in response to an applied electrical switching signal, each said plasma switch including; an enclosure for containing an ionizable gas; thermionic hollow cathode means, and anode means, disposed inside the enclosure; the hollow cathode means axially discharging therefrom an ionized plasma of the gas; the anode means being disposed to extract electrons from the plasma discharged from the hollow cathode means; keeper electrode means disposed between the hollow cathode means and the anode means for sustaining plasma discharge of the gas between the hollow cathode means and the keeper electrode means in response to a first voltage applied to the keeper electrode means; and control electrode means disposed between the keeper electrode means and the anode means for causing the plasma to extend from the hollow cathode means to the anode means in response to the switching signal, whereby the voltage of the control electrode means is made positive relative to the hollow cathode means thereby electrically connecting the hollow cathode means and the anode means with a low forward voltage drop, the pressure of the ionizable gas being low enough to maintain voltage standoff between the control electrode and the anode means; the hollow cathode means, anode means, keeper electrode means, and control electrode means being configured such that the plasma will extend from the hollow cathode means substantially only to the keeper electrode means when the switching signal applied to the control electrode makes the voltage of the control electrode non-positive relative to the cathode means, thereby interrupting the electrical connection between the anode means and the hollow cathode means thereby disconnecting the anode means from the hollow cathode means. - View Dependent Claims (22, 23, 24)
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25. An inverter/converter, comprising:
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direct current power source means; voltage transformer means having primary winding means connected in circuit with the power source means, and secondary winding means; rectifier means connected in circuit with the secondary winding means; and at least one plasma switch connected in circuit to connect the power source means to the primary winding means in response to an applied electrical switching signal, each said plasma switch including; an enclosure for containing an ionizable gas; hollow cathode means, and anode means, disposed inside the enclosure; the hollow cathode means axially discharging therefrom an ionized plasma of the gas; the anode means being disposed to radially extract electrons from the plasma discharged from the hollow cathode means; keeper electrode means disposed between the hollow cathode means and the anode means for sustaining plasma discharge of the gas between the hollow cathode means and the keeper electrode means in response to a first voltage applied to the keeper electrode means; and control electrode means disposed between the keeper electrode means and the anode means for causing the plasma to extend from the hollow cathode means to the anode means in response to a second voltage applied to the control electrode means which makes the control electrode positive relative to the hollow cathode means, thereby electrically connecting the hollow cathode means and anode means; the hollow cathode means, anode means, keeper electrode means, and control electrode means being configured such that the plasma will extend from the hollow cathode means substantially only to the keeper electrode means when the second voltage on the control electrode is changed to make the control electrode non-positive relative to the hollow cathode means. PG,33 - View Dependent Claims (26, 27, 28)
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Specification