Which of the following is NOT a type of television camera tube?

The term "Digitalicon" is not recognized as a type of television camera tube. The other options represent well-established types of camera tubes used in television technology.

The Vidicon is a widely used camera tube that converts optical images into electronic signals and was integral in early television broadcasting. Similarly, the Image Orthicon is another significant type that enhances the sensitivity and resolution needed for television imaging. The Plumbicon is also a notable tube that improves image quality and contrasts for television. Each of these tubes has specific applications and historical relevance in the development of video technology.

In contrast, "Digitalicon" does not exist in this context, correlating more with digital technologies rather than analog camera tube technology, making it the correct answer in this question.