According to {HEAD ~ an aspect} of {TAIL ~ the invention}, there is provided a grid electrode that is substantially thin plate shaped and that includes an opening section having plural openings and a frame section that surrounds the opening section 
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According to { HEAD ~ an aspect } of { TAIL ~ the invention } , there is provided a grid electrode that is substantially thin plate shaped and that includes an opening section having plural openings and a frame section that surrounds the opening section
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH