Sterilant gas generating system

1 . A system for generating a target gas by using microwave energy, comprising:

a chamber for containing gas;

a gas converting device having a gas inlet and a gas outlet connected to the chamber and adapted to convert gas received through the gas inlet into a target gas and to eject the target gas into the chamber through the gas outlet; and

a gas recirculating mechanism coupled to the chamber and the gas inlet of the converting means and operative to move the gas contained in the chamber to the gas inlet of the converting means.

2 . A system as recited in claim 1 , wherein the gas converting device is configured to apply microwave energy to effect gas conversion and comprises:

at least one nozzle including:

a housing having a generally cylindrical space formed therein, the space forming a gas flow passageway; and

a rod-shaped conductor disposed in the space and operative to transmit microwave energy along a surface thereof so that the microwave energy transmitting along the surface excites gas flowing through the space.

3 . A system as recited in claim 2 , wherein the housing includes a through hole as the gas inlet.

4 . A system as recited in claim 2 , further comprising a waveguide in which a portion of the rod-shaped conductor is disposed and to which the nozzle is secured.

5 . A system as recited in claim 2 , further comprising an electrical insulator disposed in the space and adapted to hold the rod-shaped conductor relative to the housing.

6 . A system as recited in claim 1 , wherein the gas recirculating mechanism comprises:

a gas line having one end operatively connected to the chamber and another end operatively connected to the gas inlet of the converting means; and

a pump disposed in the gas line and operative to generate a gas flow in the gas line.

7 . A system as recited in claim 1 , further comprising a sensor for measuring a concentration of the target gas in the chamber.

8 . A system as recited in claim 1 , wherein the target gas is selected from the group consisting of NO 2 , NO, CO 2 , ClO 2 , SO 2 , H 2 O 2 , O 3 , EtO, and any mixture thereof.

9 . A system as recited in claim 1 , wherein the gas converting device comprises:

a microwave cavity for containing microwave energy;

a tube formed of material transparent to microwave energy and passing through the cavity and having two ends corresponding to the gas inlet and the gas outlet, respectively; and

the microwave cavity containing sufficient microwave energy such that gas flowing through the tube is excited by the microwave energy contained in the microwave cavity when the gas passes through the microwave cavity.

10 . A system as recited in claim 9 , wherein a cross-sectional dimension of the microwave cavity is reduced at a location nearby the tube.

11 . A system as recited in claim 9 , wherein the tube is formed of dielectric material.

12 . A system as recited in claim 9 , wherein the gas flowing through the tube is excited into plasma when the gas passes through the microwave cavity.

13 . A system for generating a target gas, comprising:

a microwave generator for generating microwave energy;

a power supply connected to the microwave generator for providing power thereto;

a microwave cavity;

a waveguide operatively connected to the microwave cavity for transmitting microwave energy thereto from the microwave generator;

an isolator for dissipating microwave energy reflected from the microwave cavity;

at least one nozzle coupled to the microwave cavity and including:

a housing having a generally cylindrical space formed therein and a through hole, the space forming a gas flow passageway and being in fluid communication with the through hole; and

a rod-shaped conductor disposed in the space and having a portion extending into the microwave cavity for receiving microwave energy and operative to transmit microwave energy along a surface thereof so that the microwave energy transmitted along the surface excites gas flowing through the space into the target gas;

a chamber operatively coupled to the space and adapted to receive the target gas from the nozzle; and

a gas recirculating mechanism coupled to the chamber and the through hole formed in the housing and operative to move the gas contained in the chamber to the through hole.

14 . A system as recited in claim 13 , wherein the gas recirculating device comprises:

a gas line having one end operatively connected to the chamber and another end operatively connected to the through hole formed in the housing; and

a pump disposed in the gas line and operative to generate a gas flow in the gas line.

15 . A system as recited in claim 13 , further comprising a sensor for measuring a concentration of the target gas in the chamber.

16 . A system for generating a target gas, comprising:

a microwave generator for generating microwave energy;

a power supply connected to the microwave generator for providing power thereto;

a microwave cavity;

a waveguide operatively connected to the microwave cavity for transmitting microwave energy thereto from the microwave generator;

an isolator for dissipating microwave energy reflected from the microwave cavity; a chamber for containing gas;

a tube formed of material transparent to microwave and passing through the cavity and having an upstream end and a downstream end and configured to convert gas flowing therethrough into a target gas by use of the microwave energy in the microwave cavity;

said chamber operatively coupled to the downstream end of the tube and adapted to receive the target gas from the tube; and

a gas recirculating mechanism coupled to the chamber and the upstream end of the tube and operative to move the gas contained in the chamber to the upstream end of the tube.

17 . A system as recited in claim 16 , wherein the gas recirculating mechanism comprises:

a gas line having one end operatively connected to the chamber and another end operatively connected to the upstream end of the tube; and

a pump disposed in the gas line and operative to generate a gas flow in the gas line.

18 . A system as recited in claim 16 , further comprising a sensor for measuring a concentration of the target gas in the chamber.