Many applications of microwave heating require the use of multi-mode microwave cavities. Such applications are for example some small continuous-flow production processes, solid food thermal processing, glass and minerals melting etc. The microwave heating in multi-mode cavities is known to be a very complicated process depending on various physical parameters. They may be the geometry of the heating chamber, the structure of the processed material (heterogeneous or homogeneous), the orientation and the shape of the material, its surface (smooth or non-smooth), its dielectric properties, temperature dependant microwave permittivity, and the actual distribution of the microwave energy.
The problem for control of microwave heating becomes hard to formalize in such a general setting. Therefore there are number of different attempts for narrowing it. They vary from an expensive and complicated computer modeling software to an empirical application of mechanical devices such as stirrers and turntables. Whatever the approach is, it needs real experimental validation of the predicted/anticipated microwave energy pattern, which is necessary for obtaining the desired uniform heat release within the irradiated material. This validation represents a proof of the actual distribution of the microwave energy in the processing (resonant) cavity for the specific application. Our company offers precisely that - simple tool for visual proof of microwave energy patterns. We developed a method for mapping density distribution of microwave power irradiation by means of visualization the fields with electromagnetic intensity using microwave active compositions (MWAC). They may be coated on an object with a random shape and could be reversible or irreversible.

As it is seen above, under microwave irradiation our Reversible Microwave Active Composition loses its color intensity at certain spots, while the irreversible version gains color intensity. Also what is shown is animations of static test, as the spots on the coated object represent exactly where the surface has been hit by microwaves. If the test is performed under dynamic conditions (used in industry applications), then not just spots, but the whole area of microwave irradiation could be determined. The color intensity of the microwave active compositions is corresponding to the intensity of microwave heating. Examples of dynamic tests could be seen below:

The process transpires in mild conditions, without any special requirements. Our Microwave Active Compositions are water based and their components are not toxic or dangerous to human health. Testing would be done in any multi-mode microwave cavity used for Microwave Thermal Processing.
Our Reversible Microwave Active Composition could be used for testing multiple times, while the Irreversible one would be used just once.
Depending of the specific application, both types would be of great assistance to scientists and engineers researching microwave heated processes or designing microwave power equipment.
If the MWAC is coated on a non-absorbent (transparent) to microwaves material with no load in the processing chamber, then the spots on the model will correspond to the generic (empty cavity) electromagnetic intensity pattern. The latter will change if a microwave absorbent object is used for testing. The magnitude of transformation depends on an irradiated model's geometry and dielectric properties. Some microwave absorptive materials with high dielectric loss factor may not be used for testing. Contact us for consideration of your particular testing material.