US 12,278,095 B2
System and method for remote sensing a plasma
Patrick J. McNally, Dublin (IE); and Sean Kelly, Dublin (IE)
Assigned to DUBLIN CITY UNIVERSITY, (IE)
Filed by DUBLIN CITY UNIVERSITY, Dublin (IE)
Filed on Sep. 16, 2022, as Appl. No. 17/946,189.
Application 17/946,189 is a continuation of application No. 16/498,049, granted, now 11,476,098, previously published as PCT/EP2018/057556, filed on Mar. 23, 2018.
Claims priority of application No. 1705202 (GB), filed on Mar. 31, 2017.
Prior Publication US 2023/0230821 A1, Jul. 20, 2023
Int. Cl. H01J 37/32 (2006.01)
CPC H01J 37/32963 (2013.01) [H01J 37/32972 (2013.01); H01J 37/3299 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A system to remotely monitor a plasma, the system comprising: an electromagnetic antenna positioned outside a plasma chamber; a spectrum analyzer coupled to the electromagnetic antenna which measures a plurality of signals received by the electromagnetic antenna to determine whether the electromagnetic antenna is detecting a near electromagnetic field signal from a plasma source in the plasma chamber, said determination being made by measuring fall-off of the signals received as a function of distance from the plasma chamber such that a measurement of a signal which falls-off at a rate of 1/r3 denotes a measurement of a near electromagnetic field signal; the antenna is positioned in proximity to a non-conduction external access port to detect the near electromagnetic field signal of the plasma source in the plasma chamber, and the spectrum analyzer is configured to analyze low power signal levels across a wide frequency band.