Method for detecting dark discharge and device utilizing the method
A method of applying RF energy to an object in a cavity is disclosed. In some embodiments, the method may include applying to the object a first amount of RF energy at power increasing from an initial power level to a final power level; and if an electrical discharge occurs, stopping RF energy application for a period sufficient to allow the electrical discharge to decay. The method may further include applying to the object a second amount of RF energy after the period ends. The second amount of RF energy may be applied at intermediate power, higher than the initial power level and lower than the final power level.
1. A method of heating an object in an energy application zone by applying RF energy to the energy application zone without causing a visible electrical discharge, the method comprising:
applying RF energy to the energy application zone at a first power level,
measuring a value of an electromagnetic response parameter indicative of the electromagnetic response of the energy application zone to the applying of RF energy;
intermitting the application of RF energy after the value of the electromagnetic response parameter is measured to be outside a predetermined range and before a visible electrical discharge occurs;
renewing RF energy application after intermission at a second power level, wherein the second power level is lower than the first power level; and
performing a sequence of RF energy application events with an intermission event between each two succeeding energy application events in the sequence, wherein a power level of each RF energy application event is lower than a power level of a preceding RF energy application event in the sequence,
wherein each intermission event is sufficiently long to allow discharge, if occurring during the RF energy application event preceding the intermission event, to decay completely.
2. The method according to claim 1 , wherein the electromagnetic response parameter comprises at least one of: field intensity in the energy application zone, field amplitude in the energy application zone, S parameters, Z parameters, T parameters, ABCD parameters, gamma parameters, or dissipation ratios.
3. The method according to claim 1 , wherein the intermitting the application of RF energy comprises intermitting for a period of predetermined length.
4. The method according to claim 1 , wherein the intermitting the application of RF energy comprises intermitting for a period of at least 10 milliseconds.
5. The method according to claim 1 , further comprising increasing the first power level when the value of the electromagnetic response parameter is measured to be inside the predetermined range.
6. The method according to claim 1 , further comprising:
measuring a value of the electromagnetic response parameter indicative of the electromagnetic response of the energy application zone to the RF energy application at the second power level,
intermitting the RF energy application if the value is measured to be outside the predetermined range, and
renewing the RF energy application at a third power level, lower than the second power level.
7. The method according to claim 1 , wherein an amount of RF energy applied at the second power level is larger than an amount of RF energy applied at the first power level by a factor of at least 50 times.
8. The method according to claim 1 , wherein the intermitting RF energy application starts within 10 milliseconds after the electromagnetic response parameter is measured to be outside the predetermined range.
9. The method according to claim 1 , further comprising:
applying RF energy to the energy application zone using a plurality of excitation setups,
wherein RF energy application at each of the plurality of excitation setups comprises:
applying RF energy to the energy application zone at a first power level,
measuring a value of an electromagnetic response parameter indicative of the electromagnetic response of the energy application zone to the RF energy application;
intermitting the application of RF energy after the value of the electromagnetic response parameter is measured to be outside a predetermined range and before visible electrical discharge occurs; and
renewing RF energy application after the intermission at a second power level, wherein the second power level is lower than the first power level.
10. The method according to claim 9 , wherein intermitting RF energy application comprises intermitting RF energy application at the plurality of excitation setups at the same time.
11. The method according to claim 9 , wherein RF energy applications at differing excitation setups interlace.
12. A method of heating an object in an energy application zone by applying RF energy to the energy application zone without causing a visible electrical discharge, the method comprising:
applying RF energy to the energy application zone at a first power level,
measuring a value of an electromagnetic response parameter indicative of the electromagnetic response of the energy application zone to the applying of RF energy;
intermitting the application of RF energy after the value of the electromagnetic response parameter is measured to be outside a predetermined range and before a visible electrical discharge occurs; and
renewing RF energy application after intermission at a second power level, wherein the second power level is lower than the first power level; and
performing a sequence of RF energy application events with an intermission event between each two succeeding energy application events in the sequence, wherein a power level of each RF energy application event is lower than a power level of a preceding RF energy application event in the sequence,
wherein after the sequence of RF energy application events is performed, RF energy is applied at a power level lower than or equal to a power level of a penultimate RF energy application event in the sequence.
13. The method according to claim 12 , wherein each intermission event is performed after measuring a value of the electromagnetic response parameter outside the predetermined range.
14. The method according to claim 12 , wherein each intermission event is sufficiently long to allow discharge, if occurred during the RF energy application event preceding the intermission event, to decay completely.