The Pulse Schedule and Waveform Control

The pulse schedule is the time-programmed plan of references and actuator waveforms that defines a discharge before it begins.

What a pulse schedule is

Before a shot, operators prepare a pulse schedule: a set of time-dependent waveforms specifying the target plasma current, shape, density, heating, and every other reference the controllers will track, plus the feedforward actuator commands. It is the executable plan for the discharge, translated from a physics scenario into concrete waveforms.

References versus commands

A waveform can be either a reference for a feedback loop to track, or a direct feedforward command to an actuator. Most quantities use both: a feedforward command gets the actuator into the right range, and a feedback reference corrects the remainder. The schedule holds both, and the control system knows which loop owns each waveform.

Segmentation

Schedules are usually divided into phases such as breakdown, ramp-up, flat-top, and ramp-down. Each phase can enable different controllers and different limits. Transitions between phases are triggered either by time or by a condition being met, for example flat-top starting when the target current is reached rather than at a fixed clock time.

Editing and validation

A schedule is checked before it runs: waveforms are validated against actuator limits, rates of change, and consistency between coupled quantities. A schedule that asks for more heating than exists, or a current rise faster than the supply can drive, is rejected before it reaches the machine. Flight-simulator runs give a final check.

In the Kronos program

For the Hyperion breeder, pulse schedules encode the ramp to 9.86 megaamperes, the shape at negative triangularity, and the flat-top at the design operating point. Because the machine is in simulation ahead of construction in the second quarter of 2027, schedules are developed and validated entirely against models, so the first hardware discharges follow already-vetted waveforms.