Before revision: The helical gyrotron electron beam can amplify an applied microwave signal similarly to the way a straight electron beam amplifies in classical microwave tubes such as the klystron, so there are a series of gyrotrons which function analogously to these tubes.
After revision: The helical gyrotron electron beam can amplify an applied microwave signal similarly to the way a straight electron beam amplifies in classical microwave tubes such as the klystron, so there is a series of gyrotrons which function analogously to these tubes.