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Tesla Coil Spark Course - Image Requirements

This document lists all images needed for the interactive lesson application, organized by section. Each entry includes specifications for creation.

Total Images Required: 45+

Current Status (Updated 2025-10-10)

Images Complete: 37 / 45+

Status	Count	Description
✓ Generated (matplotlib)	22	High-quality programmatically generated graphs, plots, tables
⚠ Placeholder	15	Placeholders created with descriptions for manual creation
❌ Specification Only	7	Circuit diagrams - see CIRCUIT-SPECIFICATIONS.md
➖ Optional/Future	1	Nice-to-have images for future enhancement

Generated Images (22)

Fundamentals (4): complex-plane-admittance, phase-angle-visualization, phase-constraint-graph, admittance-vector-addition
Optimization (4): power-vs-resistance-curves, frequency-shift-with-loading, drsstc-operating-modes, loaded-pole-analysis
Spark Physics (6): energy-budget-breakdown, epsilon-by-mode-comparison, thermal-diffusion-vs-diameter, voltage-division-vs-length-plot, length-vs-energy-scaling, qcw-vs-burst-timeline
Advanced Modeling (7): capacitance-matrix-heatmap, resistance-taper-initialization, power-distribution-along-spark, current-attenuation-plot, lumped-vs-distributed-comparison, position-dependent-bounds, validation-total-resistance
Shared (1): complex-number-review

Manual Creation Required

Circuit Diagrams (7): See CIRCUIT-SPECIFICATIONS.md for detailed specs
FEMM Screenshots (5): Require professional electrostatic simulations
Photography (3): High-speed photography of actual sparks
Complex Diagrams (7): Flowcharts, feedback loops, etc.

Scripts:

generate_images.py - Generates all 22 matplotlib images
generate_placeholders.py - Creates 15 placeholder images with specs
Both scripts are rerunnable and include documentation

Quick Status Reference

Image #	Name	Status
1	field-lines-capacitances	⚠ Placeholder (FEMM)
2	geometry-to-circuit	❌ Circuit Spec
3	complex-plane-admittance	✓ Generated
4	phase-angle-visualization	✓ Generated
5	phase-constraint-graph	✓ Generated
6	current-paths-diagram	❌ Circuit Spec
7	admittance-vector-addition	✓ Generated
8	impedance-matching-concept	⚠ Placeholder (Diagram)
9	power-vs-resistance-curves	✓ Generated
10	hungry-streamer-feedback-loop	⚠ Placeholder (Diagram)
11	thevenin-measurement-setup	⚠ Placeholder (Diagram)
12	thevenin-equivalent-circuit	❌ Circuit Spec
13	frequency-shift-with-loading	✓ Generated
14	drsstc-operating-modes	✓ Generated
15	loaded-pole-analysis	✓ Generated
16	electric-field-enhancement	⚠ Placeholder (FEMM)
17	femm-field-plot-example	⚠ Placeholder (FEMM)
18	energy-budget-breakdown	✓ Generated
19	epsilon-by-mode-comparison	✓ Generated
20	thermal-diffusion-vs-diameter	✓ Generated
21	spark-channel-persistence-sequence	⚠ Placeholder (Photo)
22	streamers-vs-leaders-photos	⚠ Placeholder (Photo)
23	streamer-to-leader-transition-sequence	⚠ Placeholder (Photo/Diagram)
24	voltage-division-vs-length-plot	✓ Generated
25	capacitive-divider-circuit	❌ Circuit Spec
26	length-vs-energy-scaling	✓ Generated
27	qcw-vs-burst-timeline	✓ Generated
28	lumped-model-schematic	❌ Circuit Spec
29	femm-geometry-setup-lumped	⚠ Placeholder (FEMM)
30	maxwell-matrix-extraction	⚠ Placeholder (Diagram)
31	lumped-model-validation-checks	⚠ Placeholder (Diagram)
32	distributed-model-structure	❌ Circuit Spec
33	femm-geometry-setup-distributed	⚠ Placeholder (FEMM)
34	capacitance-matrix-heatmap	✓ Generated
35	partial-capacitance-transformation	⚠ Placeholder (Diagram)
36	resistance-taper-initialization	✓ Generated
37	iterative-optimization-convergence	⚠ Placeholder (Diagram)
38	power-distribution-along-spark	✓ Generated
39	current-attenuation-plot	✓ Generated
40	lumped-vs-distributed-comparison	✓ Generated
41	position-dependent-bounds	✓ Generated
42	spice-implementation-methods	⚠ Placeholder (Diagram)
43	validation-total-resistance	✓ Generated
44	tesla-coil-system-overview	❌ Circuit Spec
45	complex-number-review	✓ Generated

Part 1: Fundamentals (8 images)

1. field-lines-capacitances.png

Location: lessons/01-fundamentals/assets/ Referenced in: fund-02 (Basic Circuit Model)

Description: 3D visualization showing electric field lines between topload (spherical or toroidal) and a cylindrical spark channel.

Details:

Show field lines for two cases side-by-side:
- Left: C_mut field lines (coupling between topload and spark)
- Right: C_sh field lines (spark to ground plane)
Use different colors: Blue for C_mut, Red for C_sh
Label key features: topload, spark channel, ground plane
Add dimension arrows showing spark length
Include legend with typical values (C_mut ~ 8 pF, C_sh ~ 6 pF for 3-foot spark)

Suggested Format: PNG, 1200x600 px, high contrast for dark/light mode

2. geometry-to-circuit.png

Location: lessons/01-fundamentals/assets/ Referenced in: fund-02 (Basic Circuit Model)

Description: Side-by-side comparison showing physical geometry translating to circuit schematic.

Details:

Left side: 3D rendering of topload with spark
- Toroid or sphere topload
- Cylindrical spark extending downward
- Ground plane at bottom
- Arrows indicating the two capacitive paths
Right side: Circuit schematic
- Topload node at top
- (R || C_mut) in series with C_sh to ground
- Clear node labels
- Component values shown

Suggested Format: PNG, 1400x700 px

3. complex-plane-admittance.png

Location: lessons/01-fundamentals/assets/ Referenced in: fund-03 (Admittance Analysis)

Description: Complex plane plots showing Y and Z phasors.

Details:

Two complex planes side-by-side:
- Left: Admittance (Y) plane with Re{Y} horizontal, Im{Y} vertical
- Right: Impedance (Z) plane with Re{Z} horizontal, Im{Z} vertical
Show example phasor on each: Y = 10 + j15 mS, Z = 30 - j45 Ω
Mark angles θ_Y and φ_Z
Show relationship φ_Z = -θ_Y with arrows
Use grid lines for readability
Color code: Conductance/Resistance (blue), Susceptance/Reactance (red)

Suggested Format: PNG, 1200x600 px

4. phase-angle-visualization.png

Location: lessons/01-fundamentals/assets/ Referenced in: fund-04 (Phase Angles)

Description: Impedance phasors showing different phase angles and their meanings.

Details:

Show 5 impedance phasors on single complex plane:
1. Pure resistive (φ = 0°)
2. Slightly capacitive (φ = -30°)
3. Balanced (φ = -45°)
4. More capacitive (φ = -60°)
5. Highly capacitive (φ = -75°)
Label each with physical interpretation
Highlight -45° as "theoretical matched" with note: "Often impossible for Tesla coils"
Show typical spark range (-55° to -75°) as shaded region
Include power factor values for each

Suggested Format: PNG, 1000x800 px

5. phase-constraint-graph.png

Location: lessons/01-fundamentals/assets/ Referenced in: fund-05 (Phase Constraint)

Description: Graph of minimum achievable phase angle vs capacitance ratio.

Details:

X-axis: r = C_mut/C_sh (0 to 3)
Y-axis: φ_Z,min (degrees, 0° to -90°)
Plot curve: φ_Z,min = -atan(2√[r(1+r)])
Mark critical point r = 0.207 where φ_Z,min = -45°
Shade "impossible region" above curve
Add horizontal line at -45° with label "Traditional 'matched' target"
Mark typical Tesla coil region (r = 0.5 to 2.0)
Include annotations for geometric examples

Suggested Format: PNG, 1000x700 px

6. current-paths-diagram.png

Location: lessons/01-fundamentals/assets/ Referenced in: fund-07 (Measurement Port)

Description: Complete Tesla coil diagram showing all current paths.

Details:

Full coil schematic: primary, secondary, topload, spark
Show and label ALL current paths:
1. I_spark (through spark resistance)
2. I_displacement (topload to ground capacitance)
3. I_coupling (primary to secondary capacitive coupling)
4. I_secondary_sections (distributed capacitance to ground)
5. I_base (total current at base)
Use different colors/line styles for each current path
Show I_base = I_spark + I_displacement + I_coupling + ...
Highlight correct measurement port (topload-to-ground)
Mark incorrect measurement location (I_base) with X

Suggested Format: PNG, 1000x1200 px (vertical)

7. admittance-vector-addition.png

Location: lessons/01-fundamentals/assets/ Referenced in: fund-03 (Admittance Analysis)

Description: Vector diagram showing parallel admittance addition.

Details:

Show two branches: Y₁ = G + jB₁ and Y₂ = jB₂
Vector addition: Y_total = Y₁ + Y₂
Graphical parallelogram method
Label Re{Y} and Im{Y} components
Show how parallel combination differs from series

Suggested Format: PNG, 800x600 px

8. impedance-matching-concept.png

Location: lessons/01-fundamentals/assets/ Referenced in: fund-06 (Why Not 45 Degrees)

Description: Conceptual diagram comparing ideal vs. constrained matching.

Details:

Show two scenarios side-by-side:
- Ideal: Load impedance can be anywhere (full circle), conjugate match achievable
- Constrained: Load impedance confined to sector (Tesla coil reality)
Highlight φ_Z,min boundary
Mark R_opt_power and R_opt_phase locations
Show -45° target outside feasible region

Suggested Format: PNG, 1200x600 px

Part 2: Optimization (7 images)

9. power-vs-resistance-curves.png

Location: lessons/02-optimization/assets/ Referenced in: opt-01 (Two Resistances)

Description: Graph of power delivered vs. resistance, showing both optimal points.

Details:

X-axis: Resistance R (log scale, 1 kΩ to 10 MΩ)
Y-axis: Power delivered P (kW)
Plot P(R) curve with clear peak at R_opt_power
Mark R_opt_power with vertical line and label
Mark R_opt_phase with different vertical line
Show phase angle φ_Z(R) on secondary Y-axis
Annotate: "R_opt_power maximizes power" and "R_opt_phase minimizes |φ_Z|"
Include typical values: R_opt_power ~ 60 kΩ, R_opt_phase ~ 100 kΩ

Suggested Format: PNG, 1200x800 px

10. hungry-streamer-feedback-loop.png

Location: lessons/02-optimization/assets/ Referenced in: opt-02 (Hungry Streamer)

Description: Feedback loop diagram showing self-optimization mechanism.

Details:

Circular diagram with 6 steps:
1. More power → Joule heating (I²R)
2. Higher temperature → thermal ionization
3. Increased n_e → higher conductivity
4. Lower R → closer to R_opt
5. Better matching → more power extracted
6. Loop back to step 1
Use arrows showing flow
Add constraint boxes: R_min, R_max, source limits
Show equilibrium point: R_actual ≈ R_opt_power
Color code: Power (red), Temperature (orange), Conductivity (blue)

Suggested Format: PNG, 1000x1000 px

11. thevenin-measurement-setup.png

Location: lessons/02-optimization/assets/ Referenced in: opt-03 (Thévenin Method)

Description: Two diagrams showing Z_th and V_th measurement procedures.

Details:

Top: Z_th measurement
- Tesla coil circuit with primary drive OFF
- 1V AC test source at topload
- Current measurement arrow
- Labels: "Drive OFF", "Measure I_test", "Z_th = 1V / I_test"
Bottom: V_th measurement
- Tesla coil circuit with primary drive ON
- No load (open circuit at topload)
- Voltage measurement
- Labels: "Drive ON", "No spark load", "Measure V_th"

Suggested Format: PNG, 1000x1000 px (vertical)

12. thevenin-equivalent-circuit.png

Location: lessons/02-optimization/assets/ Referenced in: opt-04 (Thévenin Calculations)

Description: Thévenin equivalent with spark load.

Details:

Simple circuit: V_th source → Z_th → Z_spark (load)
Show voltage divider relationship
Label currents and voltages
Add power formula: P = 0.5|V_th|²Re{Z_spark}/|Z_th+Z_spark|²
Show typical values: Z_th ~ 100 - j2400 Ω, V_th ~ 350 kV

Suggested Format: PNG, 800x600 px

13. frequency-shift-with-loading.png

Location: lessons/02-optimization/assets/ Referenced in: opt-06 (Frequency Tracking)

Description: Graph showing resonant frequency shift as spark grows.

Details:

X-axis: Spark length (meters, 0 to 3)
Y-axis: Resonant frequency (kHz)
Plot two curves:
- Lower pole frequency (decreasing with length)
- Upper pole frequency (increasing slightly with length)
Mark unloaded resonance f₀
Show C_sh increasing annotation (~ 2 pF/foot)
Typical shift: 200 kHz → 175 kHz for 2 m spark
Color code poles, add labels

Suggested Format: PNG, 1000x700 px

14. drsstc-operating-modes.png

Location: lessons/02-optimization/assets/ Referenced in: opt-06 (Frequency Tracking)

Description: Three timing diagrams showing different DRSSTC operating modes.

Details:

Three horizontal timelines:
1. Fixed frequency: Square wave, constant frequency despite loading
2. PLL tracking: Frequency adjusts as spark grows (show freq change)
3. Programmed sweep: Frequency follows predetermined curve
X-axis: Time (ms)
Y-axis: Frequency or voltage
Show spark growth underneath each
Annotate pros/cons for each mode
Color code drive signal (blue), actual resonance (red)

Suggested Format: PNG, 1200x800 px

15. loaded-pole-analysis.png

Location: lessons/02-optimization/assets/ Referenced in: opt-06 (Frequency Tracking)

Description: Frequency domain showing coupled resonances.

Details:

X-axis: Frequency (kHz, 150-250)
Y-axis: |V_topload| (kV)
Plot transfer function showing two poles (peaks)
Show unloaded case (sharp peaks)
Overlay loaded case (broader, shifted peaks)
Mark operating frequency choices
Annotate: "Wrong: operate at fixed f₀", "Right: track loaded pole"

Suggested Format: PNG, 1000x700 px

Part 3: Spark Physics (12 images)

16. electric-field-enhancement.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-01 (Field Thresholds)

Description: Field enhancement at spark tip vs. average field.

Details:

Two side-by-side field plots from FEMM:
- Left: Smooth topload (no spark), showing E_average
- Right: With spark tip, showing E_tip with enhancement
Color gradient showing field magnitude
Mark E_tip location with annotation: κ × E_average
Show tip enhancement factor κ ≈ 2-5
Include scale bar and values

Suggested Format: PNG, 1400x700 px

17. femm-field-plot-example.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-02 (Voltage Limits)

Description: FEMM electrostatic solution showing field distribution.

Details:

Complete FEMM simulation output
Toroid topload at 350 kV
2-meter spark extending down
Color-coded field magnitude (rainbow scale)
Equipotential lines overlaid
Ground plane at bottom
Field values annotated at key points
Show E_propagation threshold line (e.g., 0.5 MV/m)

Suggested Format: PNG, 800x1200 px (vertical)

18. energy-budget-breakdown.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-03 (Energy Per Meter)

Description: Pie chart showing energy distribution per meter of spark.

Details:

Pie chart with segments for:
- Ionization energy (40-50%)
- Channel heating (20-30%)
- Radiation losses (10-20%)
- Shock wave / acoustic (5-10%)
- Electrohydrodynamic work (5-10%)
Label each segment with percentage
Note total ε = 10 J/m (QCW example)
Include annotation: "Minimum theoretical: ~0.5 J/m"

Suggested Format: PNG, 800x800 px

19. epsilon-by-mode-comparison.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-04 (Empirical Epsilon)

Description: Bar chart comparing ε values by operating mode.

Details:

X-axis: Operating mode (QCW, Hybrid DRSSTC, Hard-pulsed Burst)
Y-axis: ε (J/m), log scale, 1-100
Three bars with error ranges:
- QCW: 5-15 J/m (green, efficient)
- Hybrid: 20-40 J/m (yellow, moderate)
- Burst: 30-100+ J/m (red, inefficient)
Annotate physical reasons (leader vs streamer dominance)
Include photos/sketches of typical spark appearance for each

Suggested Format: PNG, 1200x800 px

20. thermal-diffusion-vs-diameter.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-05 (Thermal Memory)

Description: Graph of thermal time constant vs. channel diameter.

Details:

X-axis: Channel diameter d (μm to cm, log scale)
Y-axis: Thermal time constant τ (ms, log scale)
Plot curve: τ = d²/(4α)
Mark key points:
- d = 100 μm → τ ~ 0.1 ms (streamer)
- d = 1 mm → τ ~ 12 ms
- d = 5 mm → τ ~ 300 ms (leader)
Shade regions: "Streamer regime", "Leader regime"
Add annotation for convection effects (longer persistence)

Suggested Format: PNG, 1000x700 px

21. spark-channel-persistence-sequence.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-05 (Thermal Memory)

Description: Time-lapse sequence showing channel cooling.

Details:

5-6 frames showing spark channel over time:
- t = 0 ms: Bright, hot channel
- t = 1 ms: Still visible
- t = 5 ms: Fading
- t = 20 ms: Nearly gone (streamer)
- t = 100 ms: Completely dissipated (streamer) OR still visible (leader)
Use false color to show temperature
Label each frame with time and approximate temperature
Show two tracks: thin streamer vs thick leader

Suggested Format: PNG, 1500x600 px

22. streamers-vs-leaders-photos.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-06 (Streamers vs Leaders)

Description: High-speed photography comparing streamer and leader appearance.

Details:

Two photos side-by-side or top/bottom:
- Top: Burst mode - purple/blue, highly branched streamers
- Bottom: QCW mode - white/orange, thick straight leaders
Same scale for size comparison
Annotations pointing out:
- Branch density
- Channel diameter
- Color differences
- Straightness vs. branching
Include camera settings and coil parameters

Suggested Format: PNG, 1200x1000 px

23. streamer-to-leader-transition-sequence.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-06 (Streamers vs Leaders)

Description: 6-step diagram showing transition mechanism.

Details:

Six sequential panels showing evolution:
1. Initial streamers (thin, branched, purple)
2. Current begins flowing (heat accumulation)
3. Channel heating (color shift to blue-white)
4. Leader forms at base (thick, bright)
5. Leader propagates (tip launches new streamers)
6. Full leader with streamer corona at tip
Arrows showing progression
Temperature scale on side (1000 K → 20000 K)
Time scale (μs → ms)

Suggested Format: PNG, 1500x1000 px

24. voltage-division-vs-length-plot.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-07 (Capacitive Divider)

Description: Graph showing how V_tip decreases as spark grows.

Details:

X-axis: Spark length L (meters, 0 to 3)
Y-axis: V_tip / V_topload (ratio, 0 to 1)
Plot curve: V_tip = V_topload × C_mut/(C_mut + C_sh(L))
Show C_sh increasing linearly with L
Mark where E_tip = E_propagation (growth stalls)
Annotate: "Sub-linear scaling"
Include typical values: C_mut = 10 pF, C_sh = 6.6 pF/m

Suggested Format: PNG, 1000x700 px

25. capacitive-divider-circuit.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-07 (Capacitive Divider)

Description: Circuit diagram showing voltage division.

Details:

Vertical stack:
- V_topload at top
- C_mut (with R in parallel)
- V_tip at junction
- C_sh to ground
Show voltage divider formula
Annotate how C_sh grows with length
Include example calculation

Suggested Format: PNG, 600x800 px (vertical)

26. length-vs-energy-scaling.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-08 (Freau Relationship)

Description: Log-log plot showing L vs E scaling for different modes.

Details:

X-axis: Energy E (Joules, log scale, 1 to 1000)
Y-axis: Spark length L (meters, log scale, 0.1 to 10)
Plot three curves:
- Burst mode: L ∝ √E (slope = 0.5)
- QCW ramp: L ∝ E^0.7 (slope = 0.7)
- Ideal linear: L ∝ E (slope = 1.0, dashed reference)
Label each with operating mode
Add data points from real measurements
Annotate physical reasons for sub-linear scaling

Suggested Format: PNG, 1000x800 px

27. qcw-vs-burst-timeline.png

Location: lessons/03-spark-physics/assets/ Referenced in: phys-05, phys-08

Description: Side-by-side timing diagrams comparing QCW and burst operation.

Details:

Two horizontal timelines:
- Top: QCW (10-20 ms ramp)
  - Power gradually increasing
  - Spark length growing continuously
  - Channel staying hot throughout
- Bottom: Burst mode (100-500 μs pulse)
  - High peak power
  - Short growth window
  - Channel cools between pulses
Show power, length, temperature on each
Annotate key differences
Time scale in ms

Suggested Format: PNG, 1400x800 px

Part 4: Advanced Modeling (16 images)

28. lumped-model-schematic.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-01 (Lumped Model)

Description: Clean circuit schematic of lumped spark model.

Details:

Three-terminal network:
- Topload (input port)
- Spark tip (internal node)
- Ground (reference)
Components clearly shown:
- C_mut between topload and spark tip
- R between topload and spark tip (parallel with C_mut)
- C_sh from spark tip to ground
Add node labels and component values
Show integration with full coil circuit (secondary, etc.)

Suggested Format: PNG, 1000x600 px

29. femm-geometry-setup-lumped.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-02 (FEMM Extraction Lumped)

Description: FEMM geometry window showing setup for lumped model.

Details:

Axisymmetric geometry:
- Toroidal topload (cross-section shown)
- Single cylindrical spark segment
- Ground plane
- Outer boundary
Materials labeled (air, perfect conductor)
Dimensions annotated
Boundary conditions marked
Mesh visible (not too dense, showing structure)

Suggested Format: PNG, 800x1000 px (vertical)

30. maxwell-matrix-extraction.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-02 (FEMM Extraction Lumped)

Description: Diagram showing Maxwell matrix extraction process.

Details:

FEMM capacitance matrix output (2×2):
```
[C_11  C_12]
[C_21  C_22]
```
Arrows showing extraction:
- C_mut = |C_12| = |C_21|
- C_sh = C_22 + C_12
Sign convention clearly explained
Example values shown
Visual representation of what each capacitance means (field lines)

Suggested Format: PNG, 1000x700 px

31. lumped-model-validation-checks.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-02 (FEMM Extraction Lumped)

Description: Flowchart of validation procedure.

Details:

Decision tree format:
1. Check matrix symmetry → Pass/Fail
2. Check C_sh vs. empirical rule → Within factor 2?
3. Mesh convergence → Refine and recheck
4. Boundary distance → Far enough?
5. Calculate R_opt → Physical range?
Color code: Green (pass), Yellow (warning), Red (fail)
Include typical pass criteria

Suggested Format: PNG, 800x1000 px (vertical)

32. distributed-model-structure.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-03 (Distributed Model)

Description: Circuit diagram of nth-order distributed model.

Details:

Vertical cascade of n segments (show n=5 for clarity):
- Topload at top
- Segment 1: [C_01][R_1][C_1,gnd]
- Segment 2: [C_12][R_2][C_2,gnd]
- ...
- Segment n: [C_n-1,n][R_n][C_n,gnd]
Show current direction arrows
Label voltage at each node (V_0, V_1, ..., V_n)
Add note: "Typically n = 5-20"
Highlight complexity vs. lumped model

Suggested Format: PNG, 600x1200 px (vertical)

33. femm-geometry-setup-distributed.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-04 (FEMM Extraction Distributed)

Description: FEMM geometry for distributed model with multiple segments.

Details:

Axisymmetric view:
- Toroid topload
- 10 cylindrical segments stacked
- Each segment labeled (1-10)
- Ground plane
- Outer boundary
Show segment numbering
Equal length segments clearly visible
Dimensions annotated
Materials and boundaries labeled

Suggested Format: PNG, 800x1200 px (vertical)

34. capacitance-matrix-heatmap.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-04 (FEMM Extraction Distributed)

Description: Heatmap visualization of 11×11 capacitance matrix.

Details:

Color-coded matrix (11 rows × 11 columns)
Diagonal elements (large positive) in red/yellow
Off-diagonal elements (smaller, some negative) in blue
Symmetry visible
Annotate:
- Row/column 0: Topload
- Rows/columns 1-10: Segments
Include colorbar with scale (pF)
Mark nearest-neighbor vs. distant coupling

Suggested Format: PNG, 1000x1000 px

35. partial-capacitance-transformation.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-04 (FEMM Extraction Distributed)

Description: Diagram showing Maxwell → Partial capacitance transformation.

Details:

Two matrices side-by-side:
- Left: Maxwell matrix (with negative off-diagonals)
- Right: Partial capacitance matrix (all positive)
Arrows showing transformation formulas
Example for 3×3 case (easier to visualize)
Physical interpretation of partial capacitances
Note: "All SPICE capacitors must be positive"

Suggested Format: PNG, 1400x700 px

36. resistance-taper-initialization.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-05 (Resistance Optimization)

Description: Graph showing initial resistance distribution.

Details:

X-axis: Position along spark (0 = base, 1 = tip)
Y-axis: Resistance R[i] (log scale, Ω)
Plot three curves:
- Uniform initialization (flat line, wrong)
- Linear taper (straight line, better)
- Quadratic taper (recommended, R = R_base + (R_tip - R_base)×pos²)
Shade physical bounds R_min(pos) and R_max(pos)
Mark typical values at base and tip

Suggested Format: PNG, 1000x700 px

37. iterative-optimization-convergence.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-05 (Resistance Optimization)

Description: Convergence plot showing resistance values over iterations.

Details:

X-axis: Iteration number (0 to 5)
Y-axis: Resistance (log scale, kΩ to MΩ)
Multiple curves: one for each segment (10 total)
Show convergence:
- Base segments (fast, 1-2 iterations)
- Mid segments (moderate, 2-3 iterations)
- Tip segments (slow, 3-4 iterations or flat)
Horizontal lines showing convergence criteria (±1%)
Color code by position (gradient base → tip)

Suggested Format: PNG, 1200x800 px

38. power-distribution-along-spark.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-05, model-06

Description: Bar chart showing power dissipation per segment.

Details:

X-axis: Segment number (1-10, base to tip)
Y-axis: Power dissipated (kW)
Bar chart with values decreasing from base to tip
Typical pattern: high at base, peak at segment 2-3, decay to tip
Annotate percentages (e.g., segment 3 = 38% of total)
Add cumulative line (reaching 100% at tip)
Include total power value

Suggested Format: PNG, 1200x700 px

39. current-attenuation-plot.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-05, model-06

Description: Graph of current magnitude along spark.

Details:

X-axis: Position along spark (m, 0 to 2.5)
Y-axis: |I| / |I_base| (normalized current, 0 to 1)
Plot curve showing exponential-like decay
Mark segment boundaries
Typical values:
- Base: 100%
- Middle: 70%
- 3/4 point: 50%
- Tip: 35%
Include annotation about displacement current

Suggested Format: PNG, 1000x700 px

40. lumped-vs-distributed-comparison.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-03, model-06

Description: Table comparing lumped vs. distributed models.

Details:

Two-column comparison table:
- Lumped Model:
  - Single R, C_mut, C_sh
  - Fast simulation (0.1 s)
  - Good for <10 foot sparks
  - Impedance matching studies
- Distributed Model:
  - n segments (10-20)
  - Slow simulation (100-200 s)
  - Accurate for any length
  - Spatial detail needed
Color code: Green (advantage), Yellow (neutral), Red (disadvantage)
Include "When to use each" decision guide

Suggested Format: PNG, 1200x800 px

41. position-dependent-bounds.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-05 (Resistance Optimization)

Description: Graph showing R_min and R_max vs position.

Details:

X-axis: Position (0 = base, 1 = tip)
Y-axis: Resistance (log scale, Ω)
Two curves:
- R_min[i] = 1 kΩ + (10 kΩ - 1 kΩ) × position
- R_max[i] = 100 kΩ + (100 MΩ - 100 kΩ) × position²
Shade feasible region between curves
Plot typical optimized R distribution within region
Annotate physical meaning (hot leader at base, cold streamer at tip)

Suggested Format: PNG, 1000x700 px

42. spice-implementation-methods.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-04 (FEMM Extraction Distributed)

Description: Three circuit diagrams showing SPICE implementation options.

Details:

Three side-by-side schematics:
1. Partial capacitance: All positive capacitors to ground
2. Controlled sources: VCCS implementing C_ij dV/dt
3. Nearest-neighbor: Simplified with only adjacent couplings
Label pros/cons of each:
- Partial: Accurate, complex transformation
- Controlled: Direct, requires behavioral sources
- Nearest-neighbor: Simple, approximate
Show 3-node example for each

Suggested Format: PNG, 1500x600 px

43. validation-total-resistance.png

Location: lessons/04-advanced-modeling/assets/ Referenced in: model-05 (Resistance Optimization)

Description: Chart showing expected R_total ranges.

Details:

Bar chart with ranges:
- Very low frequency (<100 kHz): 1-10 kΩ
- Standard (200 kHz), QCW/leader: 5-50 kΩ
- Standard (200 kHz), burst/streamer: 50-300 kΩ
- High frequency (400+ kHz): 100-500 kΩ
X-axis: Operating condition
Y-axis: Total R (log scale, kΩ)
Color code: Green (typical), Yellow (edge case), Red (check simulation)
Include dependence notes: R ∝ 1/f, R ∝ L

Suggested Format: PNG, 1000x700 px

Shared / General Images (2 images)

44. tesla-coil-system-overview.png

Location: assets/shared/ Referenced in: Multiple lessons

Description: Complete Tesla coil system diagram with all components labeled.

Details:

Show full system:
- Primary circuit (tank cap, primary coil, switching)
- Secondary coil
- Topload
- Spark
- Ground connections
Label all major components
Show coupling coefficient
Indicate measurement points
Clean, professional schematic style

Suggested Format: PNG, 1400x1000 px

45. complex-number-review.png

Location: assets/shared/ Referenced in: fund-01 (Introduction)

Description: Quick reference for complex number operations.

Details:

Four quadrants showing:
- Rectangular form (a + jb)
- Polar form (r∠θ)
- Euler form (re^(jθ))
- Complex conjugate (a - jb)
Conversion formulas
Multiplication, division, addition rules
Complex plane with example
Common electrical engineering conventions (j = √-1)

Suggested Format: PNG, 1000x800 px

Screenshot Requirements (FEMM)

Several lessons require actual FEMM screenshots. These should be taken from real simulations:

FEMM interface overview (model-02, model-04)
Mesh generation example (model-02)
Electrostatic solution with field plot (phys-02, model-02)
Capacitance matrix output (model-02, model-04)
Boundary condition setup (model-02)

Format Specifications

General Guidelines:

File format: PNG with transparency where appropriate
Resolution: Minimum 1000px on longest dimension
Color scheme: Support both light and dark mode viewing
Text: Minimum 14pt font size for labels
Accessibility: High contrast, colorblind-friendly palettes
Compression: Optimize for web (target <500 KB per image)

Tools Recommended:

Circuit diagrams: Inkscape, Draw.io, LTspice screenshots
Graphs/plots: Python matplotlib, MATLAB, or similar
3D geometry: Blender, FEMM 3D view, CAD software
Photography: High-speed camera (if available) or stock images

Priority Levels

High Priority (Create first): 1-6, 9-11, 16-19, 28-30 (Core concepts, most referenced)

Medium Priority: 7-8, 12-15, 20-27, 31-37 (Supporting material)

Low Priority (Can use placeholders initially): 38-45 (Nice-to-have, less critical for learning)

Notes for Artists/Designers

Maintain consistent style across all images
Use course color scheme (define: primary, secondary, accent colors)
Ensure equations are typeset properly (LaTeX or similar)
Add version numbers to images for tracking updates
Create SVG sources where possible for future editing
Include brief image captions in the markdown lessons

Document Version: 1.0 Last Updated: 2025-10-10 Total Images: 45+ Estimated Creation Time: 40-60 hours

34 KiB Raw Blame History

Tesla Coil Spark Course - Image Requirements

Current Status (Updated 2025-10-10)

Generated Images (22)

Manual Creation Required

Quick Status Reference

Part 1: Fundamentals (8 images)

1. field-lines-capacitances.png

2. geometry-to-circuit.png

3. complex-plane-admittance.png

4. phase-angle-visualization.png

5. phase-constraint-graph.png

6. current-paths-diagram.png

7. admittance-vector-addition.png

8. impedance-matching-concept.png

Part 2: Optimization (7 images)

9. power-vs-resistance-curves.png

10. hungry-streamer-feedback-loop.png

11. thevenin-measurement-setup.png

12. thevenin-equivalent-circuit.png

13. frequency-shift-with-loading.png

14. drsstc-operating-modes.png

15. loaded-pole-analysis.png

Part 3: Spark Physics (12 images)

16. electric-field-enhancement.png

17. femm-field-plot-example.png

18. energy-budget-breakdown.png

19. epsilon-by-mode-comparison.png

20. thermal-diffusion-vs-diameter.png

21. spark-channel-persistence-sequence.png

22. streamers-vs-leaders-photos.png

23. streamer-to-leader-transition-sequence.png

24. voltage-division-vs-length-plot.png

25. capacitive-divider-circuit.png

26. length-vs-energy-scaling.png

27. qcw-vs-burst-timeline.png

Part 4: Advanced Modeling (16 images)

28. lumped-model-schematic.png

29. femm-geometry-setup-lumped.png

30. maxwell-matrix-extraction.png

31. lumped-model-validation-checks.png

32. distributed-model-structure.png

33. femm-geometry-setup-distributed.png

34. capacitance-matrix-heatmap.png

35. partial-capacitance-transformation.png

36. resistance-taper-initialization.png

37. iterative-optimization-convergence.png

38. power-distribution-along-spark.png

39. current-attenuation-plot.png

40. lumped-vs-distributed-comparison.png

41. position-dependent-bounds.png

42. spice-implementation-methods.png

43. validation-total-resistance.png

Shared / General Images (2 images)

44. tesla-coil-system-overview.png

45. complex-number-review.png

Screenshot Requirements (FEMM)

Format Specifications

Priority Levels

Notes for Artists/Designers

34 KiB

Raw Blame History