Code that controls nuclear fusion: What programming language is used? | David Kirtley

Quick Overview

The code controlling nuclear fusion experiments, particularly those involving pulsed magnetic fields like those used by Helion, is primarily written in Fortran, with some supporting code in Python and Java, because Fortran remains the fastest language for the necessary high-speed numerical and plasma physics simulations required to manage the system's rapid firing sequences.

Key Points: The primary programming language used for controlling the fusion systems, especially for high-speed calculations, is Fortran, which predates modern high-level languages. Fortran is still widely used in fields like computational physics and aerospace engineering due to its speed in numerical computing. The systems require extremely fast control—operations occur on the microsecond to millisecond scale—which necessitates low-level programming like Fortran or assembly language. Modern simulations, particularly for magnetohydrodynamics (MHD) and plasma behavior, are often performed using advanced tools built upon these older languages. Helion's pulsed systems achieve magnetic fields greater than 100 Tesla for microseconds, contrasting with steady-state systems operating around 20 Tesla continuously. The density (n), temperature (T), and confinement time (tau) product (nTtau) must exceed a break-even point, as defined by the Lawson Criterion, for fusion to be viable. The experimental approach involves pre-programming sequences for electrical switches and monitoring diagnostics via fiber optics due to the extreme speed of the pulses.

Context: This discussion, featuring David Kirtley on the Lex Fridman Podcast, centers on the computational and programming challenges involved in controlling advanced nuclear fusion devices, specifically those employing high-current pulsed magnetic fields like those used by Helion. The conversation contrasts the speed requirements of pulsed systems with steady-state systems and explains why older, highly optimized languages remain critical for achieving the necessary real-time control and simulation accuracy for fusion reactions.