As the topic stated,what exactly is space charge limit current??
This is utterly vague if you do not put this question in its context. If you wish that other put in time and effort to produce a thoughtful response, you should at least put in some effort to present a clear and concise question.
Is this question about the physics of vacuum tube electronics?
This is why we have to wait for the OP to come back and provide a more complete explanation. I could easily say that this is a question of charge extraction out of a photocathode as well!
Or perhaps he is referring to the reverse leakage current of a semiconductor junction?
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