Electro-magnetic acoustic transducer (EMAT) having electromagnet array for generating configurable bias magnetic field patterns

An electro-magnetic acoustic transducer (EMAT) comprising:

• an electromagnet array having a plurality of electromagnets, each electromagnet including a magnetic core and a wound coil wrapped around the magnetic core;
• an electrical coil;
• wherein the electromagnets are arranged in rows;
• the magnetic cores of the electromagnets include first and second poles, the first and second poles of each electromagnet are adjacently positioned in the row of the electromagnet;
• the first and second poles of each electromagnet have north and south magnetic polarizations, respectively, when the wound coil of the electromagnet is energized by a power supply with an electric current of one polarity whereby the electromagnet array generates a first bias magnetic field, and the first and second poles of each electromagnet have south and north magnetic polarizations, respectively, when the wound coil of the electromagnet is energized by the power supply with an electric current of an opposite polarity whereby the electromagnet array generates a different second bias magnetic field;
• and
• the electrical coil is placed relative to the electromagnet array such that (i) a first leg of the electrical coil extends over the rows across the first poles of the electromagnets and (ii) a second leg of the electrical coil extends over the rows across the second poles of the electromagnets.

An electro-magnetic acoustic transducer (EMAT) comprising:

• an electromagnet array having a plurality of electromagnets, each electromagnet including a magnetic core and a wound coil wrapped around the magnetic core;
• first and second electrical coils;
• wherein first and second ones of the electromagnets are arranged in rows across columns;
• the magnetic cores of the electromagnets include first and second poles;
• the first and second poles of the first electromagnet in each row are adjacently positioned in the row of the first electromagnet in a first one of the columns, and the first and second poles of the second electromagnet in each row are adjacently positioned in the row of the second electromagnet in a second one of the columns;
• the first and second poles of each electromagnet have north and south magnetic polarizations, respectively, when the wound coil of the electromagnet is energized by a power supply with an electric current of one polarity whereby the electromagnet array generates a first bias magnetic field, and the first and second poles of each electromagnet have south and north magnetic polarizations, respectively, when the wound coil of the electromagnet is energized by the power supply with an electric current of an opposite polarity whereby the electromagnet array generates a different second bias magnetic field;
• the first electrical coil is placed relative to the electromagnet array such that (i) a first leg of the first electrical coil extends over the rows across the first poles of the electromagnets in the first one of the columns and (ii) a second leg of the first electrical coil extends over the rows across the second poles of the electromagnets in the first one of the columns;
• and
• the second electrical coil is placed relative to the electromagnet array such that (i) a first leg of the second electrical coil extends over the rows across the first poles of the electromagnets in the second one of the columns and (ii) a second leg of the second electrical coil extends over the rows across the second poles of the electromagnets in the second one of the columns.

An electro-magnetic acoustic transducer (EMAT) comprising:

• an electromagnet array having a plurality of electromagnets, each electromagnet including a magnetic core and a wound coil wrapped around the magnetic core;
• an electrical coil having first and second coil segments;
• wherein first and second ones of the electromagnets are arranged in rows across columns;
• the magnetic cores of the electromagnets include first and second poles;
• the first and second poles of the first electromagnet in each row are adjacently positioned in the row of the first electromagnet in a first one of the columns, and the first and second poles of the second electromagnet in each row are adjacently positioned in the row of the second electromagnet in a second one of the columns;
• the first and second poles of each electromagnet have north and south magnetic polarizations, respectively, when the wound coil of the electromagnet is energized by a power supply with an electric current of one polarity whereby the electromagnet array generates a first bias magnetic field, and the first and second poles of each electromagnet have south and north magnetic polarizations, respectively, when the wound coil of the electromagnet is energized by the power supply with an electric current of an opposite polarity whereby the electromagnet array generates a different second bias magnetic field;
• and
• the first coil is placed relative to the electromagnet array such that (i) a first leg of the first coil segment extends over the rows across the first poles of the electromagnets in the first one of the columns, (ii) a second leg of the first coil segment extends over the rows across the second poles of the electromagnets in the first one of the columns, (iii) a first leg of the second coil segment extends over the rows across the first poles of the electromagnets in the second one of the columns, and (iv) a second leg of the second coil segment extends over the rows across the second poles of the electromagnets in the second one of the columns.

An electro-magnetic acoustic transducer (EMAT) comprising:

• an electromagnet array having a plurality of electromagnets, each electromagnet including a magnetic core and a wound coil wrapped around the magnetic core;
• first and second electrical coils;
• wherein first and second ones of the electromagnets are arranged in rows across columns;
• the magnetic cores of the electromagnets include first and second poles;
• the first and second poles of the first electromagnet in each row are adjacently positioned in the row of the first electromagnet in a first one of the columns, and the first and second poles of the second electromagnet in each row are adjacently positioned in the row of the second electromagnet in a second one of the columns;
• the first electrical coil is placed relative to the electromagnet array such that (i) a first leg of the first electrical coil extends over the rows across the first poles of the electromagnets in the first one of the columns and (ii) a second leg of the first electrical coil extends over the rows across the second poles of the electromagnets in the first one of the columns;
• the second electrical coil is placed relative to the electromagnet array such that (i) a first leg of the second electrical coil extends over the rows across the first poles of the electromagnets in the second one of the columns and (ii) a second leg of the second electrical coil extends over the rows across the second poles of the electromagnets in the second one of the columns;
• while the second electrical coil is not pulsed with an alternating current, the electromagnets in the first one of the columns generate a bias magnetic field for the EMAT to transmit a given type of ultrasonic wave from a first location of the electromagnet array when the first electrical coil is pulsed with an alternating current and the electromagnets in the first one of the columns are energized by a power supply;
• and
• while the first electrical coil is not pulsed with an alternating current, the electromagnets in the second one of the columns generate a bias magnetic field for the EMAT to receive a given type of ultrasonic wave from a second location of the electromagnet array when the second electrical coil is pulsed with an alternating current and the electromagnets in the second one of the columns are energized by the power supply.