What frequency should I use?
Single or multiple magnetrons?
Both of the above questions are sometimes related. Some facts about each approach are listed below:
- Magnetron efficiencies are between 50-72% for 2.45GHz compared to 80 to 87 % for high power 922 or 915MHz.
- The lower the frequency the great the penetration depth into a material.
- Field uniformity is usually better when multiple magnetrons are used.
- There are no 915 or 922MHz magnetrons less than 5kW.
- At 2.45GHz magnetron range in power from 1kW to 30kW, at 915MHz the range is from 5kW to 100kW.
- Different frequencies can initiate different energy transfer mechanisms within the material being heated, which may impact on reaction thermodynamics or product quality.
- Applicator dimensions and complexity would be much greater using multiple magnetrons.
- The larger the applicator greater will be the thermal losses and reduced microwave efficiencies. A larger applicator would be required if multiple magnetrons were used.
- In multiple magnetron installations, magnetron life is reduced due to cross coupling of power between each.
- Multiple magnetron systems provide a high degree of redundancy.
- Multiple low power magnetron generators are simple in design allowing any technician microwave technician to repair them.
- In some situations the replacement cost of low power magnetrons per kW can be higher than that of high power magnetrons.