Ion generator and ion implanter

An ion implanter comprising an ion generator,

• wherein the ion generator comprises arc chamber which defines a plasma generation space, a cathode which emits thermoelectrons toward the plasma generation space, and a repeller which faces the cathode with the plasma generation space interposed therebetween,
• wherein the arc chamber has a front slit for extracting ions,
• wherein at least part of an inner surface of the arch chamber which is exposed to the plasma generation space is made of a first refractory metal material,
• wherein the cathode has a filament that generate primary thermoelectrons and a cathode head that generates secondary thermoelectrons by heating with the primary thermoelectrons, wherein the cathode head is made of a second refractory metal material, and
• wherein a content rate of a refractory metal element by weight in the first refractory metal material is lower than a content rate of a refractory metal element by weight in the second refractory metal material.