# The DESC stellarator code suite Part 3: Quasi-symmetry optimization

@article{Dudt2022TheDS, title={The DESC stellarator code suite Part 3: Quasi-symmetry optimization}, author={Daniel Dudt and Rory Conlin and Dario Panici and Egemen Kolemen}, journal={Journal of Plasma Physics}, year={2022}, volume={89} }

The DESC stellarator optimization code takes advantage of advanced numerical methods to search the full parameter space much faster than conventional tools. Only a single equilibrium solution is needed at each optimization step thanks to automatic differentiation, which efficiently provides exact derivative information. A Gauss–Newton trust-region optimization method uses second-order derivative information to take large steps in parameter space and converges rapidly. With just-in-time…

## 8 Citations

### The DESC stellarator code suite. Part 1. Quick and accurate equilibria computations

- Computer ScienceJournal of Plasma Physics
- 2023

Comparisons of two three-dimensional equilibrium codes: VMEC, which uses a steepest-descent algorithm to reach a minimum-energy plasma state, and DESC, which minimizes the magnetohydrodynamic (MHD) force error in real space directly are detailed.

### The DESC stellarator code suite. Part 2. Perturbation and continuation methods

- PhysicsJournal of Plasma Physics
- 2023

A new perturbation and continuation method is presented for computing and analysing stellarator equilibria. The method is formally derived from a series expansion about the equilibrium condition…

### Mapping the space of quasisymmetric stellarators using optimized near-axis expansion

- PhysicsJournal of Plasma Physics
- 2022

A method is demonstrated to rapidly calculate the shapes and properties of quasi-axisymmetric and quasi-helically symmetric stellarators. In this approach, optimization is applied to the equations of…

### Optimization of quasi-symmetric stellarators with self-consistent bootstrap current and energetic particle confinement

- PhysicsPhysics of Plasmas
- 2022

Quasi-symmetry can greatly improve the confinement of energetic particles and thermal plasma in a stellarator. The magnetic field of a quasi-symmetric stellarator at high plasma pressure is…

### Direct stellarator coil optimization for nested magnetic surfaces with precise quasi-symmetry

- PhysicsPhysics of Plasmas
- 2023

We present a robust optimization algorithm for the design of electromagnetic coils that generate vacuum magnetic fields with nested flux surfaces and precise quasi-symmetry. The method is based on a…

### Single-stage stellarator optimization: combining coils with fixed boundary equilibria

- PhysicsPlasma Physics and Controlled Fusion
- 2023

We introduce a novel approach for the simultaneous optimization of plasma physics and coil engineering objectives using fixed-boundary equilibria that is computationally efficient and applicable to a…

### Unsupervised discovery of nonlinear plasma physics using differentiable kinetic simulations

- Physics, Computer ScienceJournal of Plasma Physics
- 2022

This work creates a differentiable solver for the three-dimensional partial-differential equation describing the plasma kinetics and introduces a domain-specific objective function, and performs gradient-based optimization of neural networks that provide forcing function parameters to the differentiablesolver given a set of initial conditions.

### Magnetic Fields with General Omnigenity

- Physics
- 2023

Omnigenity is a desirable property of toroidal magnetic fields that enables the confinement of trapped particles. Equilibrium solutions that approximate omnigenity have previously been discovered for…

## 35 References

### The DESC stellarator code suite. Part 1. Quick and accurate equilibria computations

- Computer ScienceJournal of Plasma Physics
- 2023

Comparisons of two three-dimensional equilibrium codes: VMEC, which uses a steepest-descent algorithm to reach a minimum-energy plasma state, and DESC, which minimizes the magnetohydrodynamic (MHD) force error in real space directly are detailed.

### The DESC stellarator code suite. Part 2. Perturbation and continuation methods

- PhysicsJournal of Plasma Physics
- 2023

A new perturbation and continuation method is presented for computing and analysing stellarator equilibria. The method is formally derived from a series expansion about the equilibrium condition…

### DESC: A stellarator equilibrium solver

- Physics
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The new code DESC is presented to solve for fixed-boundary ideal magnetohydrodynamic equilibria in stellarators. The approach directly solves the equilibrium force balance as a system of nonlinear…

### Direct construction of optimized stellarator shapes. Part 2. Numerical quasisymmetric solutions

- PhysicsJournal of Plasma Physics
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Quasisymmetric stellarators are appealing intellectually and as fusion reactor candidates since the guiding-centre particle trajectories and neoclassical transport are isomorphic to those in a…

### Gradient-based optimization of 3D MHD equilibria

- PhysicsJournal of Plasma Physics
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Using recently developed adjoint methods for computing the shape derivatives of functions that depend on magnetohydrodynamic (MHD) equilibria (Antonsen et al., J. Plasma Phys., vol. 85, issue 2,…

### Single-stage gradient-based stellarator coil design: Optimization for near-axis quasi-symmetry

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The shape gradient is a local sensitivity function defined on the surface of an object which provides the change in a characteristic quantity, or figure of merit, associated with a perturbation to…

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The results suggest that finite-build effects should be accounted for in the optimization of stellarators with low coil tolerances.

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The V3FIT code for performing equilibrium reconstruction in three-dimensional plasmas is described. It is a modular code that has the potential to be coupled with a variety of equilibrium solvers to…

### Adjoint approach to calculating shape gradients for three-dimensional magnetic confinement equilibria

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The shape gradient quantifies the change in some figure of merit resulting from differential perturbations to a shape. Shape gradients can be applied to gradient-based optimization, sensitivity…