Use when verify the interference-control provisions required for a space system or equipment exposed to electrostatic-discharge events under ECSS-E-ST-20-07C clause 4.2.4.2: categorize each event as a surface-charging-arc, an internal-charging-arc, a triboelectric-separation event or a ground-handling-event, size the arc-discharge pulse from the stored capacitance, the breakdown-voltage and the arc resistance, couple that pulse onto a victim-harness through its transfer-impedance and shield-effectiveness, compare the coupled transient against the victim transient-susceptibility threshold with the declared emi-margin, and confirm the chassis-bonding, surface-conductivity, shield-termination and transient-filtering provisions for that event family are on record. Trigger: ecss, e-st-20-electrical-scope, esd-related-emi-control, electrostatic-discharge, arc-transient-coupling, transfer-impedance, surface-charging-arc, internal-charging-arc, shield-termination, transient-susceptibility.
---
name: e2007-esd-related-emi-control
description: "Use when verify the interference-control provisions required for a space system or equipment exposed to electrostatic-discharge events under ECSS-E-ST-20-07C clause 4.2.4.2: categorize each event as a surface-charging-arc, an internal-charging-arc, a triboelectric-separation event or a ground-handling-event, size the arc-discharge pulse from the stored capacitance, the breakdown-voltage and the arc resistance, couple that pulse onto a victim-harness through its transfer-impedance and shield-effectiveness, compare the coupled transient against the victim transient-susceptibility threshold with the declared emi-margin, and confirm the chassis-bonding, surface-conductivity, shield-termination and transient-filtering provisions for that event family are on record. Trigger: ecss, e-st-20-electrical-scope, esd-related-emi-control, electrostatic-discharge, arc-transient-coupling, transfer-impedance, surface-charging-arc, internal-charging-arc, shield-termination, transient-susceptibility."
license: Apache-2.0
compliance: STANDARDS-REF
standards:
- id: ecss
reference-only: true
gated: false
domain: space-systems
pack: space-systems
compatibility: "agentskills.io SKILL.md; any SKILL.md host (Claude Code, Hermes, OpenClaw)"
metadata:
domain: space-systems
subdomain: ecss
tags: [ecss, e-st-20-electrical-scope, e2007-esd-related-emi-control, electrostatic-discharge, arc-transient-coupling, transfer-impedance, surface-charging-arc, internal-charging-arc, transient-susceptibility]
version: 0.1.0
author: Aero Agent Skills
---
# ECSS Electromagnetic Compatibility — ESD-Related EMI Control (space-systems/ecss/e2007-esd-related-emi-control)
Use when the task is the electrostatic-discharge interference-control
assessment of ECSS-E-ST-20-07C clause 4.2.4.2 — categorizing each
discharge event a system or equipment is exposed to, sizing the
arc-discharge pulse it delivers, coupling that pulse onto the victim
harness, and checking the coupled transient against the victim
transient-susceptibility threshold with a declared emi-margin.
## Domain quick reference
- Clause 4.2.4.2 treats an electrostatic-discharge event as an
interference source, not only as a damage mechanism: the arc is a
fast, broadband current pulse that couples into harnesses and
equipment ports, so the provision set is an interference-control
set (bonding, surface conductivity, shield termination, transient
filtering) rather than a single component-level protection device.
- Four event families cover the in-scope exposures. A
surface-charging-arc comes from differential charging of an external
dielectric relative to the conductive structure. An
internal-charging-arc comes from energetic electrons buried inside a
dielectric until the internal field exceeds breakdown. A
triboelectric-separation event comes from contact and separation of
dissimilar materials during deployment or release. A
ground-handling-event is the pre-launch human-body or charged-device
exposure. Each event is categorized into exactly one family before
its provisions are checked, and an unrecognized event kind is
rejected rather than assumed benign.
- The arc is modelled as a capacitive discharge through the arc
resistance: peak current is the breakdown-voltage divided by the arc
resistance, transferred charge is capacitance times breakdown-voltage,
stored energy is half the capacitance times the breakdown-voltage
squared, and the decay time constant is the product of arc resistance
and capacitance. The spectral corner frequency derived from that time
constant is what makes a small-energy arc an EMI source: a short
time constant pushes significant content into the band where harness
coupling is efficient.
- Coupling onto a victim-harness uses the surface transfer-impedance of
its shield: the open-circuit transient is peak current times the
transfer-impedance per metre times the exposed run length, reduced by
the shield-effectiveness expressed in decibels. The result is
compared with the victim transient-susceptibility threshold, and the
ratio in decibels is the emi-margin. A design is acceptable only when
that emi-margin meets or exceeds the declared requirement.
- The provision set is family-specific. A surface-charging-arc needs
surface-conductivity control and a bonded conductive path plus
terminated shields; an internal-charging-arc needs dielectric
thickness or shielding control plus bonding and transient filtering;
a triboelectric-separation event needs static-dissipative materials
and bonding; a ground-handling-event needs a controlled handling area,
operator bonding and transient filtering. A missing provision is a
finding even when the computed emi-margin passes.
## Workflow
1. Inventory every electrostatic-discharge exposure of the system and
its equipment, and categorize each one into its event family.
Reject an unrecognized event kind before it enters the assessment.
2. Size the arc-discharge pulse for each event from the stored
capacitance, the breakdown-voltage and the arc resistance; record
peak current, transferred charge, stored energy, decay time constant,
pulse duration and spectral corner frequency.
3. For each event and the victim it can reach, compute the coupled
transient from the harness transfer-impedance, the exposed run
length and the shield-effectiveness.
4. Compute the emi-margin as the decibel ratio of the victim
transient-susceptibility threshold to the coupled transient, and
compare it against the declared requirement. Treat an exactly
on-limit result as compliant by absorbing the floating-point
representation error, never by widening the requirement.
5. Check the family-specific provision set for each event and list the
provisions that are not on record.
6. Aggregate the coupling findings and the provision findings; the
system is not interference-controlled for electrostatic discharge
until both lists are empty. Report the worst emi-margin as the
driving case.
## Pitfalls
- Treating an arc as an energy problem only: a milli-joule arc that is
harmless thermally still radiates a broadband pulse, and clause
4.2.4.2 is about that interference path, not about the energy.
- Collapsing the four event families into one generic exposure — the
provision sets differ, and a surface-conductivity coating does
nothing for an internal-charging-arc driven by buried charge.
- Applying the open-circuit transient without the shield-effectiveness
term, or applying the shield-effectiveness twice by also reducing the
transfer-impedance; each is a large error in opposite directions.
- Reading a passing emi-margin as compliance while a required provision
is unrecorded — the computed coupling covers one victim and one path,
while the provision set covers the exposures that were never modelled.
- Widening the declared emi-margin requirement to make an exactly
on-limit case pass; absorb the representation error in the comparison
instead and leave the engineering requirement untouched.
- Assuming a ground-handling-event is out of scope because it happens
before launch; the latent damage and the provisions that prevent it
are part of the same interference-control set.
## Behavior contract (gate 3)
The event categorization, arc-pulse sizing, transfer-impedance
coupling, emi-margin and provision-set logic is exercised by the gate 3
contract test: scripts/test_e2007_esd_related_emi_control.py against
scripts/e2007_esd_related_emi_control_logic.py (stdlib unittest,
offline). Run: python3 scripts/test_e2007_esd_related_emi_control.py
## Compliance
- ECSS standards are freely downloadable (ESA); cite the source and
paraphrase per standards-map.yaml.
- compliance: STANDARDS-REF, gated: false.
When Claude will use it
Use when verify the interference-control provisions required for a space system or equipment exposed to electrostatic-discharge events under ECSS-E-ST-20-07C clause 4.
---
name: added-mass-coefficients-potential-flow
description: Use when you must determine the added-mass-coefficients-potential-flow virtual mass (apparent mass) of a body accelerating through an inviscid irrotational fluid from the kinetic energy of the irrotational flow it sets up: the 2-D circular cylinder rho pi R^2 and normal flat plate rho pi a^2 per unit span, the 3-D sphere two-thirds rho pi R^3, the elliptic cylinder and the prolate and oblate spheroid coefficients, plus the kinetic-energy and acceleration-reaction relations. Produces the added mass of the requested shape, its ratio to the displaced fluid mass, the fluid kinetic energy at a translation speed, the virtual mass with the body mass, and the acceleration-reaction force for the fluid inertia of unsteady motion. Trigger: added mass coefficients, virtual mass, apparent mass, acceleration reaction force, kinetic energy of irrotational flow, body accelerating in fluid, airship hull added mass, ditching float added mass, spheroid added mass.
---
---
name: aeroelastic-gust-response
description: Use when you must compute the dynamic aeroelastic response of a flexible two-degree-of-freedom typical wing section to a discrete gust with indicial unsteady aerodynamics: run the Wagner and Kussner lag-state lift model in the time domain, produce the plunge and pitch response histories for a one-minus-cosine gust, and report the dynamic magnification factor of the peak lift over the quasi-steady value plus the peak-load verdict against a limit. Produces response histories, the dynamic magnification factor, and load margin. Trigger: aeroelastic gust response, dynamic gust response, kussner function, wagner function, indicial aerodynamics, dynamic magnification factor, typical section gust, gust response history.
---
---
name: divergence-speed
description: Use when you must compute the static aeroelastic divergence condition of a lifting surface: calculate the divergence dynamic pressure from the torsional stiffness, the reference area, the chord, the lift curve slope, and the aerodynamic-center-to-shear-center offset ratio, convert it to the divergence speed at sea level, and assess the divergence margin against the design dive speed, flagging risk when the margin falls below the required 1.15 threshold. Produces the divergence dynamic pressure, the divergence speed, and a margin verdict that feed torsional stiffness sizing for divergence clearance. Trigger: divergence speed, divergence dynamic pressure, torsional stiffness, aerodynamic center, shear center, divergence margin, static aeroelastic divergence.
---
