Which phased array scan refers to the movement of the beam across a defined range of angles using the same set of elements?

The correct choice highlights the concept of azimuthal scanning, which entails the movement of the ultrasound beam across a predetermined range of angles while utilizing a consistent set of transducer elements. This method is particularly advantageous in Phased Array Ultrasonics, as it allows for the effective inspection of welds, joints, and other critical areas by achieving comprehensive coverage without the need to reposition the transducer itself.

In azimuthal scanning, the beam is electronically controlled to steer it at various angles, providing a better visualization of the internal structure of the material being inspected. This scanning technique is essential for accurately locating and characterizing defects based on their orientation and position relative to the transducer.

The other options refer to different scanning methods. For instance, a linear scan moves the beam in a straight line, covering a range of positions along a single axis rather than varying angles. An electronic scan, although it implies the use of electronic steering, does not specifically indicate the movement across a range of angles as defined in the question. Lastly, a raster scan typically denotes a systematic pattern, similar to how a printer would operate, covering an area in a grid-like fashion rather than focusing on angular movement pertinent to azimuthal scanning.