Micro machined two dimensional faraday collector grid
A system for detecting particles in a gas stream comprises a Faraday collector separating charged particles into positive and negative streams to be detected. The Faraday collector includes a plurality of interdigitated wires, with a first plurality of wires charged with a positive potential and a second plurality of wires charged with a negative potential to separate particles in the gas stream into the positive and negative streams.
1. A system for detecting particles in a gas stream comprising:
a Faraday collector separating charged particles into positive and negative streams to be detected;
said Faraday collector including a plurality of interdigitated wires, with a first plurality of said wires charged with a positive potential and a second plurality of said wires charged with a negative potential to separate particles in the gas stream into the positive and negative streams;
the potential on said fine wires being less than 20 volts; and
alternating ones of said wires being charged with the positive and negative potentials.
2. The system as set forth in claim 1 , wherein the potential is less than 10 volts.
3. The system as set forth in claim 1 , wherein a thickness of said wires is less than 100 micron, and a spacing between adjacent ones of said wires is less than 400 micron.
4. The system as set forth in claim 1 , wherein a positive bus is formed at one side of said collector and a negative bus is formed at a second side of said collector and one of said buses communicate with each of said first and second plurality of wires.
5. The system as set forth in claim 4 , wherein channels are formed between adjacent ones of said wires to receive the gas flow.
6. The system as set forth in claim 5 , wherein said Faraday collector is formed of a silicon material.
7. The system as set forth in claim 4 , wherein said bus and said wires are received in a substrate and said substrate is grounded.
8. The system as set forth in claim 1 , wherein an electric field from said Faraday collector is canceled out at less than twice a spacing between adjacent ones of said plurality of wires both upstream and downstream of said Faraday collector.
9. The system as set forth in claim 8 , wherein a thickness of said wires is less than 100 micron, and a spacing between adjacent ones of said wires is less than 400 micron.
10. The system as set forth in claim 1 , wherein a positive bus is formed at one side of said collector and a negative bus is formed at a second side of said collector and one of said buses communicate with each of said first and second plurality of wires.
11. The system as set forth in claim 1 , wherein channels are formed between adjacent ones of said wires to receive the gas flow.
12. The system as set forth in claim 1 , wherein said bus and said wires are received in a substrate and said substrate is grounded.
13. An ion mobility system comprising:
a first mechanism for imparting charge on air constituents, a second mechanism for separating ions by size, and a Faraday collector for separating charged particles into positive and negative streams to be detected; and
said Faraday collector including a plurality of interdigitated wires, with a first plurality of said wires charged with a positive potential and a second plurality of said wires charged with a negative potential to separate particles in the gas stream into the positive and negative streams;
the potential on said fine wires being less than 20 volts; and
alternating ones of said wires being charged with the positive and negative potentials.
14. The system as set forth in claim 13 , wherein said first mechanism is one of a corona discharge source and a radial active ionization source.
15. The system as set forth in claim 13 , wherein said second mechanism is one of a drift tube or a differential mobility cell.
16. The system as set forth in claim 13 , wherein a thickness of said wires is less than 100 micron, and a spacing between adjacent ones of said wires is less than 400 micron.
17. The system as set forth in claim 13 , wherein a positive bus is formed at one side of said collector and a negative bus is formed at a second side of said collector and one of said buses communicate with each of said first and second plurality of wires.
18. The system as set forth in claim 13 , wherein channels are formed between adjacent ones of said wires to receive the gas flow.
19. The system as set forth in claim 13 , wherein said bus and said wires are received in a substrate and said substrate is grounded.
20. The system as set forth in claim 13 , wherein an electric field from said Faraday collector is canceled out at less than twice a spacing between adjacent ones of said plurality of wires both upstream and downstream of said Faraday collector.