Systems and methods for monitoring temperature distribution in downhole equipment using magnetostrictive probes. In one embodiment, an ESP motor has a stator with a rotor and shaft rotatably positioned within the stator. Magnetostrictive sensors are positioned within the motor. Each magnetostrictive sensor has a transducer, a probe, and electronic circuitry coupled to the transducer. The circuitry generates an initial electrical signal that is conveyed to the transducer. The signal passes through one or more coils in the transducer, generating magnetic fields that induce an acoustic signal in the probe. The acoustic signal propagates through the probe and waves are reflected from reflection points in the probe. The transducer senses the reflected acoustic waves and provides corresponding electrical signals to the circuitry, which determines timing intervals associated with the reflected waves and uses this information to determine temperatures at one or more locations in the probe (hence in the monitored equipment).

A pickup sensor is disclosed for a magnetostrictive sensing instrument for sensing position of a magnetic field. The instrument includes an elongate tube having a near end and a distal end. A magnetostrictive wire in the tube has first and second ends. The second end is operatively secured at the tube distal end. The pickup sensor comprises a housing mounted proximate the tube near end. A pair of crystals are in the housing sandwiching the magnetostrictive wire so that interaction between an electric pulse on the magnetostrictive wire and a magnetic field produces a torsional wave on the magnetostrictive wire sensed by the pair of crystals. A pair of spring elements are mounted in the housing sandwiching the crystals to provide consistent contact force between the crystals and the magnetostrictive wire.

A magnetostrictive sensing instrument comprises a probe including a tube having a near end and a distal end. A magnetostrictive wire is in the tube. An adaptor at the tube near end includes a probe circuit comprising a drive circuit for the magnetostrictive wire, a pickup sensor, a preamplifier and a memory circuit storing calibration parameters for the probe. An instrument housing includes a control circuit. A connector is operatively disposed between the instrument housing and the adaptor and comprises electrical conductors for connecting the control circuit to the probe circuit.

A fluid property measurement system, comprising at least one waveguide. A sheath substantially surrounds the waveguide and is arranged coaxially with the waveguide. An electronic assembly is operatively coupled to the waveguide and the sheath, the electronic assembly configured to produce a first torsional ultrasonic wave signal through the waveguide, a second torsional ultrasonic wave signal through the sheath, and a longitudinal ultrasonic wave signal through at least one of the waveguide and the sheath. An energy system and a method of measuring properties of a fluid are also disclosed.