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