Search

AbstractFuel injection by means of solid cryogenic pellets is expected to provide a sound and efficient tool. Hence, the installation of a pellet launching system will be a necessity. Yet, pellets are considered as a serviceable actuator for integrated supplementary functions as, e.g., fast and efficient delivery of seeding gas, or in case needed, the pacing of edge-localized modes. Consequently, a control scheme has to be developed that is capable of mastering the simultaneous actuations covering different tasks. Our scheme relies on pellet launching by a centrifuge accelerator, providing the option for precisely predictable pellet injection sequences. In order to develop a suitable actuator control scheme, as a first step the central part was brought into service at ASDEX Upgrade. It proved operational for feedback particle flux control of a single pellet source. In a subsequent step, it is now upgraded to enable multitasked control of the JT-60SA multipellet source currently under construction. In its finally designated configuration, this control scheme provides a potential solution for a reactor-grade system.

AbstractReactor plasma core fueling requires the injection of cryogenic pellets, most probably composed of a mixture of D2and T2. Likely, pellet injection will be the most important actuator for plasma core density control. Therefore, pellet injection systems must be developed further that are capable of acting as actuator for density control. A novel control scheme is developed based on a centrifuge acceleration system. This scheme considers every available pellet launching slot and compares the current particle flux with the requested one. The response time is within the granularity of the available launching slots, in this case between 7 and 12 ms. First plasma experiments in feedforward mode showed excellent results, providing a good basis for upcoming plasma core density feedback control development activities.