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5.3.7. Parameter Reference

Parameter Name

Valid Entries

Description

Basis Set

h0.5, h1.5, h2.5, h3.5, h4.5, c1.5, c2.5, c3.5, c4.5

The basis set dictates the accuracy of the field representation within each mesh element. The higher the basis set order, the more functions are used, generally resulting in a more accurate result. For more information, see “Basis Set”.

Number of Modes to Extract

Number of modes to extract above the shift frequency.

Shift Frequency [FREQUENCY]

Only modes above this frequency will be extracted. This value should be set reasonably close to the first mode of interest to reduce computational costs.

AMR Error Estimator

Local Error Estimate, Electric Field Divergence, Electric Energy Density, Magnetic Energy Density, Total Energy Density

Determines the quantity to be used to determine where to refine the mesh during AMR.

Solve Inside Conductors

Per Material, Never, Always

This flag controls whether the solver will solve for the field inside metal conductors. This is sometimes necessary to achieve high accuracy solutions. Solving inside conductors generally increases the solution time and should not be done unless the skin-depth is comparable to the metal thickness over at least a portion of the frequency band. Otherwise, lossy metal will be approximated using impedance boundary conditions on the metal surface, which will yield sufficient accuracy in most cases without incurring the runtime performance penalty of solving inside the metal.

Phase Advance/Specification

Linear Range Count, Linear Range Increment, “Custom List Specification”

Determines how the phase advances are specified. This quantity is only used when periodic boundary conditions are present.

Cavity Calculations/Shunt Impedance Path Start Point - [LENGTH]

Start point of path used in the shunt impedance calculation.

Cavity Calculations/Shunt Impedance Path End Point - [LENGTH]

End point of path used in the shunt impedance calculation.

Cavity Calculations/Kick Factor Path Start Point [LENGTH]

Start point of path used in the kick factor calculation.

Cavity Calculations/Kick Factor Path End Point [LENGTH]

End point of path used in the kick factor calculation.

Cavity Calculations/Particle Beta

Particle beta as used in the calculation of various output quantities in the mode summary table.

Cavity Calculations/Clip Integration Paths at Structure Boundaries

True, False

If true, the paths specified for the kick factor and shunt impedance calculations are clipped by the actual mesh thus impacting the length of the integrations paths which impact the results of these calculations. If false, the length of the integration paths is strictly determined by the start and end points you specify.

Power Loss Calculations/Power Loss Type

Conductivity, Resistance

Method of specifying loss in the cavity walls that have been described with PEC boundary conditions, for use in the computation of surface losses for estimation of cavity Q and power dissipation. It is not used in the eigensolve itself.

Power Loss Calculations/Conductivity

Visible if Power Loss Calculations/Power Loss Type is "Conductivity". This is used in the computation of surface losses for estimation of cavity Q and power dissipation. It is not used in the eigensolve itself.

Power Loss Calculations/Resistance

Visible if Power Loss Calculations/Power Loss Type is "Resistance". This is used in the computation of surface losses for estimation of cavity Q and power dissipation. It is not used in the eigensolve itself.

Fields/Electric, Magnetic, and Surface Current Density, Wall Loss, etc./Output

All Modes, None

Controls field output.

Fields/Normalization/Type

Energy, Average Accelerating Gradient, Peak Volumetric, Peak Surface, Peak Axial on Axis, Average Accelerating Gradient E-Field Magnitude

Controls the manner in which the fields are normalized.

Fields/Normalization/Target

Specifies the value of the field normalization. The unit of this value depends on the value of the field normalization type.

Eigensolver/Method

Automatic, Iterative, Direct

This flag controls whether the eigensolver uses a direct or iterative method. The Direct method identifies all of the eigenmodes and then selects the appropriate ones based upon sorting criteria. The Direct method is very robust, but it scales very poorly with mesh element count. The Iterative methods converge only one, to at most a few modes of interest, but do so quite rapidly and in a fashion that scales well as the port meshes increase in element count. Except possibly for very small problems, the Iterative methods are the best choice, and the Automatic selection is equivalent to Iterative.

Eigensolver/Iterative/Convergence Tolerance

Visible if Eigensolver/Method is "Iterative". The target residual for convergence of modes. A mode is considered converged if the corresponding eigenpair (mode field pattern and propagation constant) gives a matrix equation residual less than this value.

Eigensolver/Iterative/Maximum Iterations

Visible if Eigensolver/Method is "Iterative". This is the maximum number of iterations that the iterative eigensolvers will use to converge the number of modes requested at each port.

Eigensolver/Iterative/Method

Automatic, Arnoldi, Lanczos

Visible if Eigensolver/Method is "Iterative". The iterative methods include Arnoldi and Lanczos, which implement the symmetric Arnoldi and Lanczos processes, respectively. The Automatic selection is equivalent to Lanczos.

Eigensolver/Output Messages

True, False

If true, status messages from the port eigensolver are sent to the Log.

Eigensolver/Linear Solver/Method

Automatic, Iterative, Direct

This parameter controls the type of solver that is used to solve the matrix equation(s). The options are Direct and Iterative. The Direct solver performs an LU factorization of the matrix, and the iterative method uses a variant of the preconditioned conjugate gradient (PCG) method. The Automatic selection is equivalent to Direct, and this is almost always faster than the Iterative option.

Eigensolver/Linear Solver/Iterative/Method

CG, BiStabCG, CGS, GMR

Several iterative linear solver methods are available. The CG option invokes the standard preconditioned conjugate gradient method, BiStabCG invokes the stabilized variant of biconjugate gradient, and CGS is the conjugate gradient squared method. Additional options include the generalized minimum residual method (GMR) and the quasi-minimum residual method (QMR). Of these, only GMR has the property that the residual error will reduce every iteration, but CG is generally the most efficient.

Eigensolver/Linear Solver/Iterative/Preconditioner

Jacobi, Gauss-Seidel, P-Multigrid.

Use of a matrix preconditioner improves the convergence rate of iterative methods. The Jacobi method is the most efficient in terms of computer memory. P-Multigrid uses the most computer memory but will result in very short iteration sequences for higher-order elements (it involves a factorization of a portion of the matrix, and is equivalent to using a Direct method if only the lowest order H0.5 basis set is used).

Eigensolver/Linear Solver/Iterative/Convergence Tolerance

When the residual of the matrix equation falls below this value the linear solver considers the result converged. Setting this value too low can cause very long solution times, and setting it too high will result in breakdown of the simulation.

Eigensolver/Linear Solver/Iterative/Maximum Iterations

Maximum number of iterations the linear solver will perform before stopping, irrespective of the size of the matrix equation residual.

Eigensolver/Linear Solver/Direct/Method/HMLU/Factor Accuracy Level

Automatic, Low, Medium, High, Perfect

The HMLU linear solver produces an inexact LU factorization of the system matrix that is subsequently used in an iterative loop to determine the solution vectors for port/mode excitations. The accuracy of the factor can be controlled via the “Factor Accuracy Level” solver parameter. Options are “Low”, “Medium”, “High”, “Perfect”, and “Automatic”. The “Perfect” setting yields a factor with an accuracy equivalent to that obtained using the MFLU solver, and will result in the iterative loop converging in a single step. A lower factor accuracy is faster to compute and takes less system memory, as compared to higher accuracy settings, but it can also lead to more iterations being required in the iterative loop. If the “Automatic” setting is chosen, the solver will adjust the accuracy setting as necessary to minimize runtime and memory, starting with the “Low” setting. The “Automatic” setting also allows for fail-over to a different solver if the default solver cannot solve the problem.

Field Output File

Full path to optional field output file to be used by other simulators (e.g. PT3p).

Output Meshes

True, False

If false, the solver will not output the mesh to its dataset, thus reducing computation time and dataset (and thus project) size. This can be useful in cases such as sweeps or optimizations, where mesh data is not necessary.

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