A programmable domestic microwave oven (Eaton Viking), with a 1.4 cubic feet
cavity, 600 W nominal power at 2450 MHz and ten duty-cycles, was modified
as follows (Fig. 1). A circular hole of O-1 m diameter was cut at the bottom of the
microwave oven. An acrylic pipe of equal diameter was firmly attached to the
hole, forming a duct for the delivery of temperature-modulated air at an appro-
priate rate. A fine mesh metallic screen was fitted to the top of the pipe at the
cavity floor level, to prevent microwave leakage. A second piece of the same
acrylic pipe (O-06 m long) with an attached perforated Teflon bottom plate
served as the sample holder. During a test run, the sample holder was placed in
the microwave oven just above the hole to force the conditioned air through an
evenly spaced thin layer of carrots. Uniform distribution of microwave inside
the chamber was obtained by having a mechanically-driven fan type stirrer fixed