Can a Cavity Magnetron Be Used in Reverse to Generate Resonant Frequencies?

[lufc88]

Could a cavity magnetron be done in reverse in a way so that the em waves would interact with the magnetic field and give electrons energy to jump from a cathode to an anode and would any resonant frequencies be involved?

I've read some where that this is why metal articles should not be put into microwave ovens they can reflect the radiation back into the magnetron and if the placement is right the resonance can cause the jumping electrons to fry it. Is this correct?

 

[cragar]

Why would the EM waves interact with the B field?

 

[lufc88]

I think they act on the electrons in the b field