Regenerator and regenerative refrigerator with insertion member

A regenerator which accumulates cooling generated by expansion of refrigerant gas, the regenerator comprising:

• a regenerator material which is made of a nonmagnetic material;
• a regenerator material which is made of a magnetic material;
• a container which includes a high temperature end and a low temperature end, and which is configured to accommodate the regenerator material made of the nonmagnetic material at the high temperature end side and the regenerator material made of the magnetic material at the low temperature end side,
• wherein the container further accommodates an insertion member which narrows a passage area of the refrigerant gas flowing to a region accommodating the refrigerator material made of the magnetic material so that the passage area of the low temperature end side is narrower compared to the passage area of the high temperature end side,
• wherein the insertion member is a tubular member in which a passage including a passage area decreased from one end toward the other end is provided, and is fitted to and inserted into the region of the container accommodating the regenerator material made of the magnetic material so that the one end is a high temperature side of the container and the other end is a low temperature side of the container, and
• wherein the regenerator material made of the magnetic material is accommodated in the passage provided in the insertion member.