Electrode and electrode structural body

Abstract

The electrode includes an insulator having a hollow portion (first hollow portion and second hollow portion) and a conductor provided in the hollow portion of the insulator. An edge portion of one end surface of at least the conductor is covered with the insulator.

What is claimed iso: 
     
         1 . An electrode comprising:
 a cylindrical insulator including a hollow portion; and   a conductor provided in the hollow portion of the insulator,   wherein an edge portion at one end surface of at least the conductor is covered with the insulator.   
     
     
         2 . The electrode according to  claim 1 , wherein the one end surface of the conductor is positioned inside the hollow portion in comparison with one end surface of the insulator. 
     
     
         3 . The electrode according to  claim 1 , wherein, in the hollow portion, a substance having a dielectric constant which is lower than a dielectric constant of the insulator is present between the one end surface of the conductor and one end surface of the insulator. 
     
     
         4 . The electrode according to  claim 3 , wherein the substance is an air. 
     
     
         5 . The electrode according to  claim 1 , wherein the hollow portion of the insulator includes a first hollow portion and a second hollow portion connected to the first hollow portion;
 the conductor is provided in the first hollow portion and the conductor is not present in the second hollow portion; and   an opening cross sectional area at a border between the first hollow portion and the second hollow portion is smaller than a cross sectional area of the conductor normal to an axial direction of the conductor.   
     
     
         6 . The electrode according to  claim 5 , wherein the electrode is configured to satisfy a relationship of:
   0.10≦ Aa/Ab≦ 0.90
   where Aa denotes the opening cross sectional area at the border between the first hollow portion and the second hollow portion, and Ab denotes the cross sectional area of the conductor normal to the axial direction of the conductor.   
     
     
         7 . The electrode according to  claim 5 , wherein a cross sectional area of the second hollow portion normal to an axial direction of the insulator is constant toward the border. 
     
     
         8 . The electrode according to  claim 5 , wherein a cross sectional area of the second hollow portion normal to an axial direction of the insulator changes stepwise toward the border. 
     
     
         9 . The electrode according to  claim 5 , wherein a cross sectional area of the second hollow portion normal to an axial direction of the insulator changes continuously toward the border. 
     
     
         10 . The electrode according to  claim 1 , wherein the insulator and the conductor are joined together directly and integrally by firing. 
     
     
         11 . An electrode structural body comprising a fixing member configured to fix a plurality of electrodes,
 wherein each of the electrodes comprises a cylindrical insulator including a hollow portion, and a conductor provided in the hollow portion of the insulator,   wherein an edge portion at one end surface of at least the conductor is covered with the insulator,   wherein axial directions of the electrodes are aligned and the electrodes are spaced from one another, and   wherein the electrodes are fixed to the fixing member, where the one end surface of each of the conductors is fixed to the fixing member alternately.