This Technical Note contains the design of a cryogenic benchmark experiment, introducing
alternate measurement methods such as ultrasound tomography or electric capacitance
tomography. The benchmark experiment is a redesign of baseline experiment 1 presented in
Technical Note 1 of the activity, with state-of-the-art "conventional" sensor technologies
now replaced by alternative measurement methods. In a comprehensive study different
technologies are first described, then evaluated in terms of application potential and
specifically adapted TRL scale. This includes: Ultrasound Tomography, Electrical Resistance
Tomography, Electrical Capacitance Tomography, Optical Tomography, Time of Flight
Cameras, Nuclear Magnetic Resonance Tomography, Wire-Mesh Sensors, Computed X-Ray
Tomography and Neutron Absorption. The intended application in this Note is the detection
of gas bubbles within cryogenic liquids. After assessment of parasitic heating, microgravity
compatibility and cryogenic compatibility, trade-offs are performed between sensors of the
same type. Recommendations regarding and increase in technology readiness level conclude
the sensor study and lead to the presentation of the sensor layouts of the redesigned
experiment. Finally, the sensor study recommendations are translated into an overview test
matrix as a suggestion for a step-wise sensor validation.