# Latest **URL:** https://forum.spis.org/latest.md [Latest](https://forum.spis.org/latest.md) · [Categories](https://forum.spis.org/categories.md) · [Tags](https://forum.spis.org/tags.md) --- ## [Typical Parameters - Positive/Negative SC Potential](https://forum.spis.org/t/typical-parameters-positive-negative-sc-potential/1591)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 2\ **Last updated:** [18 September 2026 23:55 UTC](https://forum.spis.org/t/typical-parameters-positive-negative-sc-potential/1591 "2026-09-18T23:55:00Z")
In one of the SPIS documents, specifically ESA-SPIS-GEO-D7-SUM-2013-03-001 ver 3 rev 5, It lays out some basic parameters to input for when you have a positive or negative potential. Some documents seem to have older in… --- ## [Ion Energy instrument](https://forum.spis.org/t/ion-energy-instrument/1604)
**Author:** [@sadi\_carnot](https://forum.spis.org/u/sadi_carnot)\ **Replies:** 0\ **Last updated:** [9 September 2026 09:34 UTC](https://forum.spis.org/t/ion-energy-instrument/1604 "2026-09-09T09:34:51Z")
To all SPIS users I am studying the interaction between a spacecraft and EP plume. I am trying to add instrument to evaluate the ion’s energy. However, I am not sure what I should choose at SPIS. I think there are a few… --- ## [Strange result of Langmuir probe sweep](https://forum.spis.org/t/strange-result-of-langmuir-probe-sweep/1593)
**Author:** [@luczagon](https://forum.spis.org/u/luczagon)\ **Replies:** 2\ **Last updated:** [4 September 2026 11:26 UTC](https://forum.spis.org/t/strange-result-of-langmuir-probe-sweep/1593 "2026-09-04T11:26:03Z")
Hello, I am doing a Langmuir probe sweep in my simulation and I get a result that seems strange. The ambient electron current drops suddenly at the end of the sweep, when the potential is positive, so as far as I know t… --- ## [Difference between potentials in potential.txt file and Average\_surface\_potential\_of\_node\_1\_(V\_,\_s)\_\_ElecNode1\_Potential.txt file](https://forum.spis.org/t/difference-between-potentials-in-potential-txt-file-and-average-surface-potential-of-node-1-v-s-elecnode1-potential-txt-file/1599)
**Author:** [@alexs](https://forum.spis.org/u/alexs)\ **Replies:** 0\ **Last updated:** [12 August 2026 09:56 UTC](https://forum.spis.org/t/difference-between-potentials-in-potential-txt-file-and-average-surface-potential-of-node-1-v-s-elecnode1-potential-txt-file/1599 "2026-08-12T09:56:25Z")
Hello everyone, I am trying to understand the difference between two potential outputs obtained from my simulation (both files from .Simulations/Run1/NumKernel/Output directory) In the file “potentials.txt”, I have val… --- ## [Circuit Definitions](https://forum.spis.org/t/circuit-definitions/1595)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [28 July 2026 08:39 UTC](https://forum.spis.org/t/circuit-definitions/1595 "2026-07-28T08:39:41Z")
I wanted to ask for some clarification on the circuit definition of a spacecraft model. Is a spacecraft and its components implicitly connected together and all floating together relative to ambient plasma? If so, if I w… --- ## [Concurrent Modification Exception error](https://forum.spis.org/t/concurrent-modification-exception-error/1594)
**Author:** [@luczagon](https://forum.spis.org/u/luczagon)\ **Replies:** 0\ **Last updated:** [23 July 2026 09:37 UTC](https://forum.spis.org/t/concurrent-modification-exception-error/1594 "2026-07-23T09:37:12Z")
Hello, While running a simulation, some time steps give this error: java.util.ConcurrentModificationException: null at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909) at java.util.ArrayList$Itr.nex… --- ## [Intermittently missing default instrument TXT outputs in Jython batch simulations (SPIS 6.1.0, Windows)](https://forum.spis.org/t/intermittently-missing-default-instrument-txt-outputs-in-jython-batch-simulations-spis-6-1-0-windows/1592)
**Author:** [@shpark](https://forum.spis.org/u/shpark)\ **Replies:** 0\ **Last updated:** [21 July 2026 01:53 UTC](https://forum.spis.org/t/intermittently-missing-default-instrument-txt-outputs-in-jython-batch-simulations-spis-6-1-0-windows/1592 "2026-07-21T01:53:18Z")
Dear SPIS developers and users, I am currently running a large number of SPIS simulations using SPIS 6.1.0 on Windows. I am using a Jython-based automation workflow to create projects, apply global parameters and materi… --- ## [Why does the body potential change more significantly when only the boom material is changed in a 3U + boom structure?](https://forum.spis.org/t/why-does-the-body-potential-change-more-significantly-when-only-the-boom-material-is-changed-in-a-3u-boom-structure/1572)
**Author:** [@shpark](https://forum.spis.org/u/shpark)\ **Replies:** 4\ **Last updated:** [21 July 2026 01:35 UTC](https://forum.spis.org/t/why-does-the-body-potential-change-more-significantly-when-only-the-boom-material-is-changed-in-a-3u-boom-structure/1572 "2026-07-21T01:35:41Z")
Hello, I am using SPIS to investigate surface charging on a 3U CubeSat equipped with a boom. The boom is assumed to have dimensions of 0.01 × 0.01 × 0.2 m and to be attached to one end of the 3U satellite. To examine ho… --- ## [Validity of SPIS for high-density laboratory Langmuir probe simulations (ne ~ 10^21 m^-3)](https://forum.spis.org/t/validity-of-spis-for-high-density-laboratory-langmuir-probe-simulations-ne-10-21-m-3/1585)
**Author:** [@surehman](https://forum.spis.org/u/surehman)\ **Replies:** 1\ **Last updated:** [8 July 2026 18:11 UTC](https://forum.spis.org/t/validity-of-spis-for-high-density-laboratory-langmuir-probe-simulations-ne-10-21-m-3/1585 "2026-07-08T18:11:03Z")
Dear SPIS Team, I hope you are well. I am currently evaluating SPIS for Langmuir probe simulations in a laboratory plasma with the following conditions: ne​∼10^21m−3 Te​∼20eV H / Ar / Air plasma Electrostat… --- ## [VTK Outputs in Batch Mode](https://forum.spis.org/t/vtk-outputs-in-batch-mode/1586)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [30 June 2026 09:43 UTC](https://forum.spis.org/t/vtk-outputs-in-batch-mode/1586 "2026-06-30T09:43:25Z")
I am trying to run some SPIS (6.2.6) simulations in batch mode (./Spis.sh -p). I want to know if there is a way to enable the export of .vtk files at the end of the simulation? I’ve tried setting the outputs exportDensi… --- ## [Mesh Modelling - Impact of Separate SC Components](https://forum.spis.org/t/mesh-modelling-impact-of-separate-sc-components/1584)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [23 June 2026 12:07 UTC](https://forum.spis.org/t/mesh-modelling-impact-of-separate-sc-components/1584 "2026-06-23T12:07:03Z")
I’ve seen many models that have there components, like the image below, not attached to the SC body. I know there are complications when meshing different geometries together–especially thin wires or panels-- what I woul… --- ## [Boundary Conditions - Presheath vs Vacuum](https://forum.spis.org/t/boundary-conditions-presheath-vs-vacuum/1583)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [23 June 2026 11:53 UTC](https://forum.spis.org/t/boundary-conditions-presheath-vs-vacuum/1583 "2026-06-23T11:53:45Z")
I’ve been reading some papers surrounding cold plasma measurements and SPIS modelling, and in them the authors were able to recreate presheath conditions to more accurately model boundary conditions (BC) in dense plasma.… --- ## [Inconsistent potential values with batch simulations](https://forum.spis.org/t/inconsistent-potential-values-with-batch-simulations/1578)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [12 June 2026 09:09 UTC](https://forum.spis.org/t/inconsistent-potential-values-with-batch-simulations/1578 "2026-06-12T09:09:34Z")
I am trying to run a batch of simulations for a SC with varying sun directions on SPIS 6.2.6. On its surface, the SC has a particle detector with a large face biased at -8V. The main global parameters changes I made are … --- ## [The error about meshing](https://forum.spis.org/t/the-error-about-meshing/1266)
**Author:** [@166117](https://forum.spis.org/u/166117)\ **Replies:** 5\ **Last updated:** [3 June 2026 05:38 UTC](https://forum.spis.org/t/the-error-about-meshing/1266 "2026-06-03T05:38:01Z")
When I finish setting the boundary condition and voltage and proceed to the next step, the SPIS prompts that there is an error in meshing. Such as “Error in UI2NUM ThreeDUnstructVolMesh.autoThinSurfaces:volume mesh surf… --- ## [Reaction analysis in SPIS](https://forum.spis.org/t/reaction-analysis-in-spis/1571)
**Author:** [@sadi\_carnot](https://forum.spis.org/u/sadi_carnot)\ **Replies:** 1\ **Last updated:** [30 April 2026 16:00 UTC](https://forum.spis.org/t/reaction-analysis-in-spis/1571 "2026-04-30T16:00:40Z")
Hello! SPIS user! I’m interested in plume analysis. So I would like to know if it is possible to simulate other reactions (elastic collision, dissociation reaction, excitation) through SPIS other than CEX reaction. Lo… --- ## [Spinning spacecraft sun flux cross-sectional area bug](https://forum.spis.org/t/spinning-spacecraft-sun-flux-cross-sectional-area-bug/1573)
**Author:** [@frejon](https://forum.spis.org/u/frejon)\ **Replies:** 1\ **Last updated:** [30 April 2026 15:10 UTC](https://forum.spis.org/t/spinning-spacecraft-sun-flux-cross-sectional-area-bug/1573 "2026-04-30T15:10:46Z")
Hi all, I think the spinning spacecraft transition is very buggy. The simulation I’ve set up can be approximated to a rotating cylinder, with a significant area. It is impossible to look at this spacecraft from any angle… --- ## [SPIS Material Properties - MSEY](https://forum.spis.org/t/spis-material-properties-msey/1551)
**Author:** [@shpark](https://forum.spis.org/u/shpark)\ **Replies:** 1\ **Last updated:** [8 April 2026 15:28 UTC](https://forum.spis.org/t/spis-material-properties-msey/1551 "2026-04-08T15:28:07Z")
Hello SPIS users, I was looking at the default material database in: SPIS-6.1.0-win64b\\resources\\defaults\\materialProperties\\SpisDefaultMaterials.xcat In the material XML, I see parameters like MSEY (maximum secondary… --- ## [Thin Wire Meshing Guidance](https://forum.spis.org/t/thin-wire-meshing-guidance/1558)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [8 April 2026 14:51 UTC](https://forum.spis.org/t/thin-wire-meshing-guidance/1558 "2026-04-08T14:51:24Z")
I am creating a model that, for simplicities sake, has a main spacecraft body (cylinder) and a thin wire coming out of the body that’s attached to a particle detector (smaller cylinder), all within a sphere of plasma. I … --- ## [Unit Conversion Error on Simulation Start Up](https://forum.spis.org/t/unit-conversion-error-on-simulation-start-up/1559)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [8 April 2026 14:49 UTC](https://forum.spis.org/t/unit-conversion-error-on-simulation-start-up/1559 "2026-04-08T14:49:11Z")
I’m running a model that has a particle detector and electric field sensor attached to a thin wire, separated by a small distance along the wire (3m). I have them defined as elec node 1 Instrument: Particle Detector and … --- ## [About TransientArtificialSource](https://forum.spis.org/t/about-transientartificialsource/1424)
**Author:** [@23131213962](https://forum.spis.org/u/23131213962)\ **Replies:** 2\ **Last updated:** [8 April 2026 14:41 UTC](https://forum.spis.org/t/about-transientartificialsource/1424 "2026-04-08T14:41:27Z")
I’m trying a transition class of artificial source, however when I set it up and get it running, the SPIS logs give me the following error: Error: SourceFluxUpdater not possible to generate for Source3 because the sampl… --- ## [Source Pulsing via Transitions](https://forum.spis.org/t/source-pulsing-via-transitions/1566)
**Author:** [@amha33291](https://forum.spis.org/u/amha33291)\ **Replies:** 2\ **Last updated:** [8 April 2026 14:39 UTC](https://forum.spis.org/t/source-pulsing-via-transitions/1566 "2026-04-08T14:39:25Z")
Hello, I am trying to turn a source on and off in SPIS, essentially by changing the current density from 0 to a positive value. However, I cannot figure out how to link my transitions table to the source density. Please… --- ## [Wire ground vs Spacecraft Ground](https://forum.spis.org/t/wire-ground-vs-spacecraft-ground/1570)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [8 April 2026 14:33 UTC](https://forum.spis.org/t/wire-ground-vs-spacecraft-ground/1570 "2026-04-08T14:33:28Z")
I am defining a circuit based on a spacecraft design with instruments on a wire boom. The wires need to be biased along with the instruments, and I was unsure if SPIS interprets wire electric nodes as the SC surface node… --- ## [VTK missing bundle ERROR](https://forum.spis.org/t/vtk-missing-bundle-error/1565)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [27 March 2026 07:52 UTC](https://forum.spis.org/t/vtk-missing-bundle-error/1565 "2026-03-27T07:52:29Z")
When starting SPIS 6.2.6 I get the error: -VTK platform specific bundles not loaded and in the terminal I get the following: -Failed to load modlue "pk-gtk-modlue" On the server I am using the package is loaded pro… --- ## [Mesh file not defined ERROR](https://forum.spis.org/t/mesh-file-not-defined-error/1564)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [6 March 2026 07:56 UTC](https://forum.spis.org/t/mesh-file-not-defined-error/1564 "2026-03-06T07:56:08Z")
I had some crashing issues when 3D meshing my spacecraft model in the GMSH 4.8.4 native to SPIS 6.2.6. I used the updated gmsh (4.15.1) to 3D mesh and it worked, however, when I try to upload the mesh file to SPIS, I get… --- ## [Is there a way to fix an out-of-memory error?](https://forum.spis.org/t/is-there-a-way-to-fix-an-out-of-memory-error/1553)
**Author:** [@shpark](https://forum.spis.org/u/shpark)\ **Replies:** 3\ **Last updated:** [12 February 2026 07:08 UTC](https://forum.spis.org/t/is-there-a-way-to-fix-an-out-of-memory-error/1553 "2026-02-12T07:08:35Z")
Hello, When I run SPIS simulations, I sometimes get a memory error and the simulation cannot continue. I’m not sure whether this is due to insufficient memory on my personal PC or an issue within the SPIS GUI. Do I … --- ## [Current Bias Capabilities](https://forum.spis.org/t/current-bias-capabilities/1554)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 1\ **Last updated:** [2 February 2026 16:03 UTC](https://forum.spis.org/t/current-bias-capabilities/1554 "2026-02-02T16:03:14Z")
Continuing the discussion from \[Archive\] Current Biased Node: Hello, I wanted to see if I could current bias now in the newer SPIS versions, or if generating a current from the plasma is still the work around for this? … --- ## [Automating SPIS (6.2.4) using python scripts](https://forum.spis.org/t/automating-spis-6-2-4-using-python-scripts/1552)
**Author:** [@jtbyrnes123](https://forum.spis.org/u/jtbyrnes123)\ **Replies:** 5\ **Last updated:** [19 January 2026 10:55 UTC](https://forum.spis.org/t/automating-spis-6-2-4-using-python-scripts/1552 "2026-01-19T10:55:28Z")
I’m trying to create a script to automate a bunch of simulations with changing parameters (electron/ion density & temp). When trying to find the correct classes to call to, I run into some problems: Classes defined by t… --- ## [About display update](https://forum.spis.org/t/about-display-update/1538)
**Author:** [@shpark](https://forum.spis.org/u/shpark)\ **Replies:** 2\ **Last updated:** [9 January 2026 05:40 UTC](https://forum.spis.org/t/about-display-update/1538 "2026-01-09T05:40:38Z")
Hello SPIS users, I have a question about using SPIS simulations. In the simulation progress window, the graph updates every 1% of progress. For heavy runs, these updates often cause lag. Is there a way to change the dis… --- ## [Why are the HET parameters in the Group Editor and SPIS initialization summary different?](https://forum.spis.org/t/why-are-the-het-parameters-in-the-group-editor-and-spis-initialization-summary-different/1500)
**Author:** [@enewtone](https://forum.spis.org/u/enewtone)\ **Replies:** 8\ **Last updated:** [9 January 2026 02:42 UTC](https://forum.spis.org/t/why-are-the-het-parameters-in-the-group-editor-and-spis-initialization-summary-different/1500 "2026-01-09T02:42:57Z")
Hello everyone, I’m trying to run one of examples called propulsion-6.1.0-2021-06-23\_09.44.07.182 available in ValidationCases-6.1.0.zip through this link. My SPIS version is SPIS-6.2.2-win64b. I’ve noticed a differenc… --- ## [SPIS freezing after Geometry/Mesh Editor](https://forum.spis.org/t/spis-freezing-after-geometry-mesh-editor/1546)
**Author:** [@luha](https://forum.spis.org/u/luha)\ **Replies:** 2\ **Last updated:** [6 January 2026 10:36 UTC](https://forum.spis.org/t/spis-freezing-after-geometry-mesh-editor/1546 "2026-01-06T10:36:56Z")
I installed and ran SPIS 6.2.5 on Windows 11 normally in the past week, with a simplified test model of just two boxes. Since yesterday and after loading a new .geo file, that maybe contained an error, SPIS does not reac… [Next page](https://forum.spis.org/latest.md?page=1)