Apparatus for inspecting degradation/damage of a material using an AC magnet, a superconducting DC magnet and a SQUID sensor

An apparatus for inspecting degradation/damage of a material comprising:

• a DC magnet for applying a DC magnetic field to an object to be inspected so as to enable measurement of a magnetic hysteresis loop of said object;
• an AC magnetic for applying a small AC magnetic field to said object to enable measurement of a minor magnetic hysteresis loop of said object;
• a magnetic sensor measuring said magnetic hysteresis loop and said minor magnetic hysteresis loop of said object;
• and
• a processing unit for detecting degradation/damage from measurement data of a magnetic characteristic of said object form said magnetic sensor and deciding the degree of degradation/damage;
• wherein said magnetic sensor is of a differential type and is placed at a position x where a change ##EQU5## in magnetic flux density B becomes zero in the magnetic fields formed by said Dc magnet and said AC magnet, whereby it is possible to cancel components induced by a magnetic coil, thereby detecting only the magnetic characteristic of said object.

An apparatus for inspecting degradation/damage of a material comprising:

• a superconducting magnet for applying a DC magnetic field to an object to be inspected so as to enable measurement of a magnetic hysteresis loop of said object;
• an AC magnet for applying a changing magnetic field to said object to enable measurement of a minor magnetic hysteresis loop of said object;
• a SQUID sensor for measuring said magnetic hysteresis loop and said minor magnetic hysteresis loop of said object;
• a cryostat for cooling said superconducting magnet and said SQUID sensor;
• and
• a processing unit responsive to measurement data of a magnetic characteristic of said object from said SQUID sensor for deciding an abnormal value from said measurement data to detect the degradation/damage of said object.

An apparatus for inspecting degradation/damage of a material comprising:

• a DC magnet for applying a DC magnetic field to an object to be inspected so as to enable measurement of a magnetic hysteresis loop of said object;
• an AC magnet for applying a small AC magnetic field to said object to enable measurement of a minor magnetic hysteresis loop of said object;
• a magnetic sensor measuring said magnetic hysteresis loop and said minor magnetic hysteresis loop of said object;
• and
• a processing unit for detecting degradation/damage from measurement data of a magnetic characteristic of said object from said magnetic sensor and deciding the degree of degradation/damage;
• wherein said AC magnet and said magnetic sensor are arranged above a surface of said object and said DC magnet is arranged at a position higher than said AC magnet and said magnetic sensor.