The ITER project was created with the goal of showing the world that fusion energy is possible and can be a major step towards having a whole new kind of commercial reactors in the energy sector. Fusion energy is obtained from the fusion reactions that take place into a plasma that is at more than 150 million degrees Celsius, which is approximately 10 times the temperature at the core of the sun. How can such a high temperature be achieved? For the operation of the reactor, an external current is induced inside of the plasma. Up to more or less 1 keV (11.5 million degrees), the plasma has some resistivity, which means that there will be Ohmic heating due to that current owing through the plasma, that can be progressively increased. But after reaching 1 keV, the plasma resistivity becomes too low to keep heating it. This makes other external heating methods essential for the operation of the reactor. One of these external heating systems is the Electron Cyclotron Resonance Heating (ECRH). It consists in heating the electrons inside the plasma by means of electromagnetic waves at the resonance frequency of a given surface in the magnetic eld. This radio frequency is generated in a device called Gyrotron. In this device, electrons are emitted from an 'electron gun' and are accelerated through a tube. These electrons oscillate in the presence of an external magnetic eld, generating the electromagnetic wave that, after being adapted, will be guided inside the reactor. The Gyrotron needs several auxiliary systems to operate such as power supplies, superconducting magnets and ion pumps. They have to work correctly and in the right moment, coordinated with the whole plant operation. The Electron Cyclotron Control System (or ECCS) is in charge of controlling the 24 Gyrotrons of the ITER reactor, together with the high voltage power supplies, the transmission lines and the launchers. The ECCS ensures the correct operation of the whole system and its protection. This project will be focused on the control system of the Gyrotron and its auxiliaries and will be divided into di erent parts. The rst part will be dedicated to give some background on how does a Gyrotron work, the physics behind it, what are its di erent components and how can these components be controlled. This will be essential for the next phase: the design of the control system, including all the auxiliary systems taking part in the operation of the Gyrotron. Since the Gyrotron is an experimental and complex device, it is vital to rst test the overall system in a simulation environment, to reduce the time and e ort needed for the tests and validation phase. Moreover, this will reduce the risk of damaging the Gyrotron and its auxiliaries allowing minimizing the design and implementation errors. This will be done creating a model on which several simulations will be run for di erent possible operating scenarios, operation modes, possible accidents and faults. Finally, after passing all the tests, the system will be implemented in a dedicated Electron Cyclotron (EC) Test Facility that was established at the SPC (Swiss Plasma Center), in Lausanne (Switzerland), for the full power testing of the real Gyrotron. The results obtained