Cool-tip thermocouple including two-piece hub

An electrosurgical system, comprising:

• an electrosurgical instrument, including:
• a handle assembly including a housing having a distal end and a proximal end, an outer shell, and a manifold insertable into the outer shell, such that upon insertion, the manifold defines a first chamber and a second chamber within the handle assembly, the second chamber disposed distal of the first chamber, the manifold including a first opening and a second opening, the first opening and the second opening defined on a proximal portion of the manifold;
• a first tube inserted into the first opening;
• a second tube inserted into the second opening;
• a tissue engaging member coupled to the distal end of the housing;
• an inner tube having a proximal portion disposed within the handle assembly and a distal portion coaxially disposed within the tissue engaging member, wherein inner tube is in direct fluid communication with the first chamber and the tissue engaging member is in fluid communication with the second chamber;
• and
• a thermocouple assembly including a first thermocouple coupled to a proximal end of the inner tube within the handle assembly and a second thermocouple coupled to a distal end of the inner tube;
• a source of treatment energy coupled to the tissue engaging member;
• and
• a source of fluid coupled to the tissue engaging member and the inner tube.