# Phase 6: QCW Spark Research — Community & Literature Survey

**Date:** 2026-02-10
**Method:** Web search across academic sources, builder documentation, and community forums
**Sources searched:** highvoltageforum.net (~20 threads), loneoceans.com (4 builds), stevehv.4hv.org, richieburnett.co.uk, hotstreamer/deanostoybox, hackaday.io, kaizerpowerelectronics.dk, pupman.com/TCML, thaumati.com, connerlabs.org, academic papers (AIP, IEEE, arXiv, AGU)
**Purpose:** Accumulate all available quantitative data on QCW spark behavior, validate against existing framework, identify new physics

---

## Summary of Findings

Three search agents surveyed 30+ forum threads, 6 builder documentation sites, and several academic papers. The findings divide cleanly into: (1) high-confidence measured data, (2) well-supported community observations, (3) unresolved hypotheses, and (4) identified measurement gaps.

The most significant finding is the **davekni voltage comparison**: a burst-mode DRSSTC at 80 kHz needs ~600 kV for 2-3 m arcs, while a QCW at 450 kHz achieves the same length at ~40 kV. This 15:1 voltage ratio proves that QCW sparks grow through sustained energy injection, not high voltage — directly validating the thermal persistence mechanism in the existing framework.

---

## 1. High-Confidence Measured Data

### 1.1 QCW Secondary Voltage is LOW

| Source | Measurement | Context |
|--------|-------------|---------|
| Steve Ward (via Uspring, HVF topic 1761) | 40 kV rising to 55 kV over ~5000 RF cycles | Arc growing to 50+ inches |
| Loneoceans (via Steve Ward simulations) | 50-70 kV despite meter-length sparks | QCW v1.0 |
| davekni (HVF topic 2397) | ~40 kV peak at 450 kHz QCW | 2-2.5 m arcs |
| davekni (same source) | ~600 kV peak at 80 kHz burst DRSSTC | 2-3 m arcs |

**Confidence:** HIGH — measured by multiple independent builders.

**Physics implication:** QCW sparks grow through sustained energy injection over 10-20 ms, not through high instantaneous voltage. The voltage rise per RF cycle is only ~3 V/cycle. This is consistent with the framework's thermal persistence model: the spark extends because the leader channel persists between cycles and conducts energy to the tip, not because the voltage is high enough to bridge the gap in a single shot.

**Contrast with burst DRSSTC:** The 15:1 voltage ratio (600 kV burst vs 40 kV QCW for similar spark lengths) is the single most important quantitative comparison in the dataset. It proves that voltage is necessary for inception but NOT for growth beyond the initial streamer reach.

### 1.2 Steve Ward 80 us Burst Ceiling

**Source:** Steve Ward, DRSSTC-0.5 (stevehv.4hv.org/DRSSTC.5.htm)

| Spark Length | Input Power | ON Time |
|-------------|-------------|---------|
| 10 inches | 33 W | ~70 us |
| 14 inches | 88 W | ~70 us |
| 15 inches | 110 W | ~70 us |
| 16 inches | 135 W | ~70 us |
| 18 inches | 180 W | 70 us, 150 BPS |

**Key observation:** "Gained almost no spark length after about 80 us of ON period."

**Confidence:** HIGH — systematic measurement with controlled variables.

**Physics implication:** This directly measures the burst-mode streamer growth saturation. After ~80 us, additional energy goes into re-heating decaying channels rather than new growth. This is consistent with tau_thermal ~ 0.1-0.2 ms for 100 um streamers — after one thermal time constant, the channels are cooling as fast as they're being heated. This is the fundamental wall that QCW overcomes by sustained drive.

### 1.3 Loneoceans Frequency Tracking Data

**Source:** Loneoceans QCW v1.0 (loneoceans.com/labs/qcw/)

| Condition | Frequency | Shift from unloaded |
|-----------|-----------|-------------------|
| Unloaded secondary | 406-409 kHz | baseline |
| With single toroid | ~392 kHz | -3.5% |
| With two stacked toroids | 361 kHz | -11% |
| With 50 cm simulated streamer | 349 kHz | -14% |
| With 1 m simulated streamer | 310 kHz | -24% |
| QCW v1.5 operating during spark | 413 → 377 kHz | -8.7% |

**Confidence:** HIGH — measured with simulated streamers (physical wires of known length, not actual plasma).

**Physics implication:** The simulated-streamer data provides clean calibration points for C_sh. A 1 m wire causes a 24% frequency shift, implying significant capacitive loading. The 8.7% shift during actual QCW operation (v1.5) is less than the simulated 1 m streamer shift, suggesting the effective capacitance of a real 1.78 m spark is less than that of a solid wire — consistent with the distributed, branched nature of real sparks having lower effective capacitance than a solid conductor.

### 1.4 Loneoceans Build Comparison Data

**QCW v1.5 (leader-dominated):**

| Parameter | Value |
|-----------|-------|
| Spark length | 1.78 m (70+ inches) |
| Secondary length | 5.55 inches |
| Spark:secondary ratio | 13:1 |
| Energy per pulse | 275 J |
| Ramp duration | 22 ms (16-17 ms rise) |
| Peak primary current | 145-160 A |
| Coupling (k) | 0.38 |
| Operating frequency | 413 → 377 kHz |

**DRSSTC 3 (streamer-dominated, for comparison):**

| Parameter | Value |
|-----------|-------|
| Spark length | 1.78-2.1 m |
| Secondary length | 27.5 inches |
| Spark:secondary ratio | 3:1 |
| Burst pulse width | 70-135 us |
| Peak primary current | 700-842 A |
| Coupling (k) | 0.148 |
| Operating frequency | 71.8-78.9 kHz |

**Physics implication:** Same absolute spark length requires a 5x longer secondary, 5x higher peak current, and ~5x lower coupling in burst mode. The spark:secondary ratio difference (13:1 vs 3:1) is the most dramatic measure of QCW's advantage. QCW achieves this with 22 ms ramp vs 70-135 us burst — 200x longer pulse.

### 1.5 Steve Conner Burst Efficiency Finding

**Source:** Steve Conner (connerlabs.org), referenced on HVF and Kaizer guide.

**Finding:** "Using a lower impedance tank circuit to draw higher peak power from the inverter, and shortening the burst length to maintain the same bang energy as before, gave longer sparks."

Short bursts of high peak power grow sparks more efficiently than long bursts of low peak power. 100 us burst works better than 150 us for the same energy.

**Confidence:** HIGH — reproducible across multiple builders.

**Physics implication:** Consistent with the power optimization framework. Higher peak power pushes the initial streamer further before the 80 us ceiling hits. The streamer can explore more space in the first ~80 us of high-power drive than in 150 us of lower-power drive.

### 1.6 VNTC Frequency Shift Under Loading

**Source:** VNTC (HVF topic 701)

| Condition | Power | Spark Length | RF Period (6 cycles) |
|-----------|-------|-------------|---------------------|
| Light corona | 50 W | 10 cm | 41 us |
| Heavy spark | 500 W | 55 cm | 42 us |

**Confidence:** HIGH — direct oscilloscope measurement.

**Physics implication:** Only 2.5% frequency shift despite 10x power increase and 5.5x spark length increase. At ~146 kHz, spark loading is primarily resistive, not capacitive. The small frequency shift means C_sh change is modest relative to the total system capacitance — consistent with the capacitive divider model.

### 1.7 Dr. Kilovolt (Jan Martis) SiC PSFB QCW

**Source:** Dr. Kilovolt (Jan Martis), referenced on HVF and 4hv.org

| Parameter | Value |
|-----------|-------|
| Topology | SiC PSFB (Phase-Shifted Full Bridge) |
| Bus voltage | 800 V |
| Coupling (k) | 0.55 |
| Spark length | 2-2.5 m |
| Peak power | ~40 kW |

**Key innovations:**
- SiC MOSFETs enable higher switching frequencies and efficiency
- Phase-shifted full bridge topology provides inherently smooth power delivery (no pulse-skip artifacts) with a "1-cosine" transfer function
- Coupling coefficient of 0.55 is among the highest documented, enabled by ferrite-assisted coupling

**Environmental sensitivity observation:** Outdoor operation produces "looping" or "curving" streamers rather than straight swords under humid or cool conditions. This is consistent with the humidity/temperature effects documented in Section 2.8 — higher humidity enhances complex-ion recombination, reducing plasma persistence and disrupting the single straight channel.

**Confidence:** HIGH — measured build parameters from an experienced builder.

### 1.8 Duane B Secondary Voltage Measurement

**Source:** HVF topic 1455

| Parameter | Value |
|-----------|-------|
| Secondary inductance | 173.8 mH |
| Secondary capacitance | 20.32 pF |
| Frequency | 84.690 kHz |
| Peak base current | 2.4 A |
| Calculated peak voltage (before breakout) | 222 kV |

Also referenced: Antonio Carlos M. de Queiroz data: 11.8" x 3.9" toroid reaching ~282 kV before sparking.

**Confidence:** HIGH for the inductance/capacitance, MODERATE for the voltage (calculated, not directly measured).

---

## 2. Well-Supported Community Observations

### 2.1 Frequency Threshold for Sword Sparks: 300-600 kHz

**Sources (independent, concordant):**

| Observer | Observation | Source |
|----------|-------------|--------|
| Mads Barnkob | "Sword characteristic shows above 400 kHz" | HVF topic 973 |
| LabCoatz (Zach Armstrong) | Below 300 kHz: "chaotic and less straight"; above 600 kHz: "more curvy" | Hackaday |
| Kaizer DRSSTC IV | QCW at ~100 kHz: "swirling" sparks, NOT straight | HVF topic 24 |
| Fat Coil builder | "Above 350 kHz, plasma exhibits growth in straight segments" | TCML Nov 2014 |
| Loneoceans SSTC3 | Straight sparks at 380-420 kHz | loneoceans.com |
| Multiple QCW builders | All successful sword-spark builds operate 300-500 kHz | Build survey |

**Confidence:** HIGH — 6+ independent observations converge on same frequency range.

**Physics interpretation (new insight for framework):** The RF half-period at 400 kHz is 1.25 us. The thermal diffusion time for a 100 um streamer is ~125 us — 100x longer than the RF period. The channel effectively sees continuous heating with negligible cooling between RF cycles.

At 50-100 kHz (half-period 5-10 us), thinner streamers (10-50 um, tau ~ 1-30 us) experience significant cooling between cycles, allowing the preferred conductive path to diffuse and branch. The channel cannot maintain a single preferred path.

At >600 kHz, the observation of "curvy" sparks may relate to different physics (skin effect, displacement current dominance, or IGBT switching artifacts at extreme frequencies).

### 2.2 Three Ramp Regimes

**Source:** Loneoceans QCW v1.5 documentation.

| Ramp Duration | Result | Interpretation |
|---------------|--------|---------------|
| Too short | "Gnarly, segmented sparks" | Insufficient time for leader transition |
| Optimal (~10-20 ms) | Straight sword sparks | Leader forms and grows continuously |
| Too long (>25 ms) | "Really hot and fat but bushy" without extra length | Leader reaches voltage-limited L_max; excess energy causes branching |

**Confidence:** HIGH — direct observation with controlled ramp variation.

**Physics interpretation:** The "too long" regime is particularly revealing. Once the leader reaches its voltage-limited length (set by the capacitive divider), additional energy has nowhere to go in the forward direction. The leader channel becomes very hot and fat (thicker → more C_sh → more voltage division → can't extend further). The excess energy drives branching because the field at the tip is below propagation threshold but the total power must be dissipated somewhere — lateral breakouts become the path.

### 2.3 Pulse-Skip Modulation Does NOT Produce Sword Sparks

**Sources:** Steve Ward, Steve Conner (2011), multiple builders on HVF.

**Finding:** Multiple experimenters tried pulse-skip approaches (omitting RF cycles to modulate power) and "could not get the sword sparks."

Steve Ward explanation: Smoothing ripples from missing pulses would require the coil to store excessive energy between cycles. Sword sparks need "relatively smooth/continuous modulation of the spark power with little ripple."

**Confidence:** HIGH — reproduced failure across multiple independent builders.

**Physics interpretation (revised):** The original interpretation ("gaps in energy delivery where the channel cools") was oversimplified. In actual DRSSTC pulse-skip implementations, the H-bridge shorts the primary tank during skip cycles (via GDT inversion or leg inhibit) while IGBTs continue switching synchronized to feedback. Primary current does not drop to zero — it decays gradually through the loaded Q. Phase coherence is maintained.

The actual mechanism is **power envelope quality**: the sawtooth current envelope (bounded by the OCD threshold) delivers approximately constant average power, not the smooth quadratic ramp (P ~ V^2 from linear voltage ramp) that true QCW provides. Per-cycle jitter from the on-off-on switching pattern prevents clean single-channel dominance. This is a **continuum**: Bresenham-algorithm pulse-density modulation creating a linear ramp produces sparks that are "more sword-like but still branch" — intermediate between coarse pulse-skip and true analog QCW. The quadratic power profile is also difficult to achieve with pulse-density modulation.

**Note:** Pulse-skip (bridge current control) is distinct from staccato (interrupter timing synchronized to AC mains). The Loneoceans SSTC3 staccato approach uses the rising AC mains waveform as a natural voltage ramp and does produce straight sparks at high frequency.

### 2.4 QCW Growth Rate: ~170 m/s

**Source:** HVF topic 973 (sword spark mechanism discussion), multiple contributors.

**Derivation:** Arc propagation speed estimated at approximately half the speed of sound (~170 m/s).

**Self-consistency check:** At 170 m/s over a 10 ms ramp, the spark grows 1.7 m. Over a 20 ms ramp, 3.4 m. These match observed QCW spark lengths (1-2 m for standard builds, 3.35 m for the Fat Coil).

**Confidence:** MODERATE — visual estimate, not directly measured with high-speed camera + ruler.

**Physics interpretation:** This is intermediate between free streamers (10^6 m/s) and natural lightning leaders (~10^4 m/s). This suggests a "driven leader" propagation mode unique to QCW: the leader advances continuously, fed by the circuit, at a rate limited by the thermal conversion of streamer to leader at the tip. The 170 m/s rate implies each "step" (streamer → heating → leader conversion) takes approximately:

```
step_length / growth_rate ~ 1 cm / 170 m/s ~ 60 us per step
```

This 60 us step time is consistent with the conductance relaxation heating time constant (tau_g = 40 us from Bazelyan) — the channel needs approximately one tau_g to heat up at each step.

### 2.5 Coupling Requirements: k >= 0.3

**Measured coupling coefficients across all documented QCW builds:**

| Builder | k | Spark:secondary ratio | Notes |
|---------|---|----------------------|-------|
| Loneoceans v1.0 | 0.32-0.35 | 7.3:1 | Initial |
| Loneoceans v1.5 (first) | 0.306 | — | Insufficient — breakthrough came at 0.38 |
| Loneoceans v1.5 (final) | 0.38 | 13:1 | Breakthrough |
| Loneoceans QCW2 | 0.365 | 10:1 | |
| flyglas | 0.391 | ~12:1 | |
| Lucasww | 0.44 | 10:1 | |
| Rafft | 0.166-0.57 | — | Tested range |
| Dr. Kilovolt (Jan Martis) | 0.55 | — | SiC PSFB, 2-2.5 m sparks |
| davekni | 0.71 | — | Ferrite-assisted, highest documented |
| Standard DRSSTC | 0.05-0.20 | 2-4:1 | For comparison |

**Confidence:** HIGH — consistent across all builds.

**Physics interpretation:** Higher coupling enables sufficient power transfer at the lower peak currents used in QCW (50-160 A vs 500-1000 A in burst DRSSTC). It also separates the pole frequencies further, making frequency tracking more robust against the shifting loaded pole. However, the Loneoceans SSTC3 (single-resonant, lower coupling) still produces sword sparks, suggesting k >= 0.3 is an engineering requirement (adequate power delivery) rather than a physics requirement (spark straightness).

### 2.6 Spark-to-Secondary Ratios

| Builder | Mode | Spark | Secondary | Ratio |
|---------|------|-------|-----------|-------|
| Steve Ward | Burst | 80" | 22" | 3.6:1 |
| Loneoceans DRSSTC3 | Burst | 70" | 27.5" | 2.5:1 |
| Loneoceans QCW v1.0 | QCW | 40" | 5.5" | 7.3:1 |
| Lucasww | QCW | 51" | 5" | 10.2:1 |
| Loneoceans QCW2 | QCW | 24" | 2.4" | 10:1 |
| Loneoceans QCW v1.5 | QCW | 70+" | 5.55" | 12.6:1 |
| Mathieu thm | QCW | 76" | 5.6" dia | 13.6:1 |
| Fat Coil | QCW | 132" | 8" | 16.5:1 |

**Confidence:** HIGH — measured across many builds.

**Physics interpretation:** The 3-5x improvement in spark:secondary ratio from burst to QCW is a direct measure of the efficiency advantage of leader-dominated growth. Leaders extend the effective electrode (the conducting channel) continuously, so the secondary length (which constrains maximum voltage) becomes less important relative to the sustained power delivery.

### 2.7 Richie Burnett Causality Reversal

**Source:** richieburnett.co.uk/operatn2.html

**Quote:** "It is not early quenching that produces good sparks, but rather good spark loading that leads to an early quench."

**Confidence:** HIGH — well-reasoned analysis from a foundational figure.

**Physics interpretation:** The causality runs: spark efficiently absorbs energy → secondary voltage drops → gap quenches (for SGTC) or primary current drops (for DRSSTC). This is the power optimization framework in action — the spark as a self-optimizing load.

### 2.8 Environmental Effects on Straightness

**Source:** davekni (HVF topic 2397)

**Observation:** Straighter arcs in warm, dry conditions; curved/branchy arcs more common outdoors (cooler, more humid).

**Confidence:** MODERATE — single observer, qualitative.

**Physics interpretation:** Consistent with the humidity data in the framework. Higher humidity → faster complex-ion recombination (25x faster for hydrated ions) → shorter effective plasma lifetime → less thermal persistence → more branching. Lower temperature → higher gas density → higher E_propagation threshold → harder to sustain growth in a single channel.

---

## 3. Community Hypotheses (Unproven but Physically Plausible)

### 3.1 Uspring's Sideways Breakout Suppression

**Hypothesis:** QCW's slowly ramped voltage keeps tip voltage low, reducing the transverse electric field component. This suppresses lateral branching because the field is only strong enough for forward propagation along the lowest-impedance path (the existing hot channel).

**Assessment:** Physically plausible but not tested. The existing hot leader channel does have much lower impedance than virgin air to the side, so a weak field would preferentially drive current forward. A strong field (as in burst mode) could overcome the impedance contrast and branch.

### 3.2 Uspring's Temperature-Frequency Coupling

**Hypothesis:** Higher operating frequency increases the time-averaged current density in the channel, raising its temperature and conductivity. A hotter channel needs less voltage to sustain, further reducing the branching field.

**Assessment:** Partially supported by the frequency threshold data. The mechanism (more RF cycles per unit time = more Joule heating per unit time) is straightforward physics. Quantitative prediction: at 400 kHz, the Joule heating rate is ~4x higher than at 100 kHz for the same peak current, because there are 4x more half-cycles per millisecond.

### 3.3 Channel Temperature: ~5000 K

**Source:** Uspring (HVF topic 973), from conductivity analysis.

**Assessment:** Not spectroscopically measured on TC sparks. However, the ~5000 K estimate is consistent with the leader temperature range in the Bazelyan framework (4000-6000 K for self-sustaining leaders). At 5000 K, associative ionization (N+O → NO+ + e) provides field-independent electron production, explaining why the channel self-sustains. This temperature is also consistent with the white/yellow visual appearance of QCW sword sparks (blackbody peak near 5000 K is in the visible range).

### 3.4 Steve Ward's "2000 Small Sparks" Model

**Source:** Steve Ward, multiple HVF threads.

**Claim:** QCW sword sparks are "a series of small sparks (2000!) build up a longer and longer ionization channel and create the appearance of a single long spark."

**Assessment:** This is a simplified description of the driven-leader mechanism. At 400 kHz over 5 ms, there are indeed ~2000 RF half-cycles, each depositing a small amount of energy. The "series of small sparks" view maps to the RF-cycle-by-cycle energy deposition that the conductance relaxation model (tau_g = 40 us) integrates over.

---

## 4. Identified Measurement Gaps

The community itself has flagged these as unmeasured:

1. **No direct arc current measurement on any QCW coil** (davekni: "Nobody has ever made arc current measurements for a QCW coil")
2. **No spectroscopic temperature measurement of QCW sparks** — 5000 K is inferred, not measured
3. **No time-resolved impedance measurement during QCW ramp** — the impedance trajectory during growth is unknown
4. **No high-speed imaging correlated with electrical waveforms in QCW mode**
5. **No measurement of energy per unit length (epsilon) for QCW sparks** — can only be bounded from total input energy and estimated system efficiency
6. **Voltage gradient in TC sparks disputed** — Uspring estimates 1.5 kV/cm, Barnkob estimates 3 kV/cm
7. **No systematic frequency sweep study** — same coil tested at 100, 200, 300, 400 kHz to isolate frequency effect

---

## 5. Academic Papers with TC-Relevant Data

### 5.1 Brelet et al. (2014) — Laser-Guided Tesla Coil Discharges

**Source:** Journal of Applied Physics, Ecole Polytechnique / ENSTA ParisTech / CNRS

**Finding:** Plasma column resistance ~ **1 kilohm per meter** in laser-guided TC discharges at 100 kHz. Discharge length increased 5x with laser guiding. Mean breakdown field: 2 kV/cm for pre-ionized 1.8 m gap.

**Caveat:** Laser-guided channels are pre-ionized, so resistance may be lower than self-propagating discharges.

### 5.2 Briels et al. (Eindhoven) — Streamer Properties

**Source:** Journal of Physics D / arXiv 0805.1376

**Findings:** Positive streamer minimum diameter 0.2 mm, minimum velocity ~10^5 m/s at 5-20 kV, up to 1.2 × 10^6 m/s at 43-60 kV. Negative discharges form only glowing clouds at same voltages.

**Confirms:** Streamer velocity hierarchy in the framework (10^5-10^6 m/s).

### 5.3 Huang et al. (2020) — Leader Reillumination

**Source:** Geophysical Research Letters

**Finding:** After a waiting time, new discharge uses the thermal imprint of the old leader channel. Luminosity wave propagates from electrode at ~10^6 m/s.

**TC relevance:** Direct evidence for the thermal persistence mechanism. At 400 kHz (2.5 us between cycles), the thermal imprint easily survives between RF half-cycles.

---

## 6. Key Numbers for Framework Integration

### 6.1 QCW Operating Parameters (Consensus Ranges)

| Parameter | QCW Range | Burst DRSSTC | Source |
|-----------|-----------|--------------|--------|
| Coupling (k) | 0.3-0.5+ | 0.05-0.2 | Build survey |
| Operating frequency | 300-600 kHz | 50-110 kHz | Build survey |
| Tank capacitance | 5-15 nF | 50-300 nF | Build survey |
| Ramp duration | 10-22 ms | N/A (burst ~70-150 us) | Build survey |
| Peak primary current | 50-200 A | 200-1000+ A | Build survey |
| Secondary voltage | 40-70 kV | 200-600 kV | Ward, davekni |
| Spark:secondary ratio | 7-16x | 2-4x | Build survey |
| Growth rate | ~170 m/s | N/A (single-shot) | HVF estimate |

### 6.2 Critical Time Comparisons

| Timescale | Value | Significance |
|-----------|-------|-------------|
| RF half-period at 400 kHz | 1.25 us | Channel heating between cycles |
| RF half-period at 100 kHz | 5 us | Channel heating between cycles |
| Streamer tau_thermal (100 um) | ~125 us | 100x longer than RF period at 400 kHz |
| Conductance tau_g (heating) | 40 us | Time to heat one "step" |
| Conductance tau_g (cooling) | 200 us | 5x longer than heating |
| Burst pulse duration | 70-150 us | Comparable to streamer tau |
| QCW ramp duration | 10-22 ms | 100x longer than tau_g |
| Streamer persistence | 1-5 ms | Exceeded by QCW ramp |
| Leader transition time | 0.5-2 ms | Within QCW ramp, exceeds burst pulse |
| Dark period cycle | 1-5 ms | Multiple cycles fit within QCW ramp |
| Burst ceiling (Ward) | ~80 us | Streamer growth saturates |

### 6.3 Energy Budget

| Quantity | Value | Source |
|----------|-------|--------|
| QCW energy per pulse | 275 J (for 1.78 m) | Loneoceans v1.5 |
| Apparent epsilon (total input / length) | 155 J/m | Derived |
| Estimated system efficiency | 30-50% | Community consensus |
| Estimated spark epsilon | 45-75 J/m | Derived (155 × 0.3-0.5) |
| Burst DRSSTC energy per bang | 5-12 J | Steve Ward |
| Burst DRSSTC average power | 33-180 W for 25-46 cm | Steve Ward DRSSTC-0.5 |

### 6.4 New Insight: Driven Leader Step Time

From the QCW growth rate of ~170 m/s and the typical leader step length of ~1 cm (Bazelyan):

```
step_time = step_length / growth_rate = 0.01 m / 170 m/s ~ 60 us
```

This 60 us step time is close to the conductance relaxation heating time constant (tau_g = 40 us), suggesting the leader advance rate is limited by how fast each new streamer segment can be heated to leader temperature. The 1.5x ratio (60 us observed vs 40 us tau_g) is reasonable given that the thermal transition also requires crossing the eta_T bottleneck.

---

## 7. Comparison with Existing Framework Predictions

### 7.1 What the Framework Got Right

- **Thermal persistence is THE key to QCW advantage** — confirmed by all data
- **Streamer-to-leader transition requires sustained drive** — confirmed
- **Capacitive voltage division limits spark length** — confirmed by frequency shift data
- **Power optimization (hungry streamer)** — confirmed by Richie Burnett's causality insight and spark loading data
- **Burst mode limited by streamer cooling** — confirmed by Steve Ward's 80 us ceiling

### 7.2 What the Framework Missed

1. **Frequency threshold for sword sparks (300-600 kHz)** — the framework discusses frequency effects on breakdown (field-thresholds.md Section 4.4, coupled-resonance.md Section 1.4) but does not predict or explain the sword-spark frequency threshold. The mechanism (RF period << streamer tau_thermal) is a straightforward extension of the existing thermal physics but was not explicitly stated.

2. **QCW secondary voltage is low (40-70 kV)** — the framework implicitly assumed higher voltages for longer sparks. The data shows QCW works by sustained energy delivery at modest voltage.

3. **Smooth, continuous drive is essential** — pulse-skip modulation fails to produce swords. The framework's growth model (dL/dt = P_stream / epsilon) does not distinguish between smooth and intermittent power delivery, but the physics requires truly continuous drive for leader maintenance.

4. **Three ramp regimes** — the "too long" regime (bushy without length) is not predicted by the framework. It arises when the leader reaches voltage-limited L_max and excess energy drives lateral branching.

5. **QCW growth rate (~170 m/s)** — this intermediate value between streamer and natural leader velocities was not predicted. It can now be derived from the framework: tau_g × step_length gives the right order of magnitude.

### 7.3 What the Framework Got Slightly Wrong

- **Leader formation voltage threshold (300-400 kV)** — this applies to single-shot impulses, NOT to QCW with sustained drive. QCW forms leaders at 40-70 kV topload voltage because the thermal ratcheting mechanism accumulates energy over thousands of cycles. The threshold should be stated as applying to single-event inception only.

---

## 8. Persons Index

| Person | Handle | Role | Key Contribution |
|--------|--------|------|-----------------|
| Steve Ward | Steve Ward | QCW inventor | Quadratic power profile, 40-55 kV measurement, 80 us burst ceiling, DRSSTC design guide |
| Richie Burnett | — | SSTC/DRSSTC pioneer | Spark loading causality reversal, pole splitting theory |
| Terry Fritz | — | Spark loading modeler | 1 pF/ft streamer capacitance model, impedance framework |
| Steve Conner | scopeboy | DRSSTC pioneer | 50 kohm impedance standard, "hungry streamer" principle, burst efficiency finding |
| Gao Guangyan | loneoceans | Prolific documenter | Most detailed QCW measurements (4 builds), frequency tracking data, three ramp regimes, SSTC3 voltage-ramp isolation |
| David Knierim | davekni | Physicist/engineer | Critical voltage comparison (600 kV burst vs 40 kV QCW for same length), fiber probe, oversized QCW |
| Uspring | Uspring | Physicist | Temperature estimates (~5000 K), voltage gradient analysis, sword spark hypotheses |
| Mads Barnkob | — | Kaizer/Admin | Frequency threshold observation (>400 kHz), voltage gradient estimate |
| Zach Armstrong | LabCoatz | Builder | Frequency window (300-600 kHz), simplified staccato QCW |
| Mathieu thm | — | Builder | 193 cm spark, 13.6x ratio record |
| flyglas | — | Builder | 170 cm spark, flashover analysis |
| Finn Hammer | hammertone | Builder | Ramp generator reference design |
| Netzpfuscher | — | UD3 designer | Phase-shift QCW controller |
| Jan Martis | Dr. Kilovolt | Builder | SiC PSFB QCW, k=0.55, 2-2.5 m sparks, ~40 kW peak, environmental sensitivity observations |
| Anders Mikkelsen | — | Forum admin | Upper/lower pole guidance |
| VNTC | — | Experimenter | 2.5% frequency shift measurement |

---

## 9. Source URLs

### Academic Papers
- Brelet et al. 2014: https://pubs.aip.org/aip/jap/article-abstract/116/1/013303/139184
- Briels et al. (arXiv): https://arxiv.org/abs/0805.1376
- Huang et al. 2020: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL086183

### Builder Documentation
- Loneoceans QCW v1.0: https://www.loneoceans.com/labs/qcw/
- Loneoceans QCW v1.5: https://www.loneoceans.com/labs/qcw15/
- Loneoceans QCW2: https://www.loneoceans.com/labs/qcw2/
- Loneoceans SSTC3: https://www.loneoceans.com/labs/sstc3/
- Steve Ward DRSSTC-0.5: https://www.stevehv.4hv.org/DRSSTC.5.htm
- Steve Ward DRSSTC design guide: https://www.stevehv.4hv.org/drsstc_design.htm
- Steve Ward DRSSTC log book: https://www.stevehv.4hv.org/drsstc_log_book.htm
- Richie Burnett operation: https://www.richieburnett.co.uk/operatn2.html
- Terry Fritz impedance model: https://hotstreamer.deanostoybox.com/TeslaCoils/Misc/impedance/impedance.html
- Kaizer DRSSTC IV: https://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-iv/
- Hackaday LabCoatz: https://hackaday.io/project/184038-building-the-worlds-simplest-qcw-drsstc/details

### Forum Threads (highvoltageforum.net)
- Sword spark mechanism (topic 973): https://highvoltageforum.net/index.php?topic=973.0
- Standard DRSSTC in QCW (topic 2361): https://highvoltageforum.net/index.php?topic=2361.0
- QCW DRSSTC ideas (topic 1761): https://highvoltageforum.net/index.php?topic=1761.0
- QCW flashover (topic 1988): https://highvoltageforum.net/index.php?topic=1988.0
- QCW questions (topic 1914): https://highvoltageforum.net/index.php?topic=1914.100
- Oversized QCW (topic 2397): https://highvoltageforum.net/index.php?topic=2397.0
- My QCW DRSSTC (topic 2621): https://highvoltageforum.net/index.php?topic=2621.0
- My first QCW (topic 3132): https://highvoltageforum.net/index.php?topic=3132.0
- Spark voltage estimation (topic 123): https://highvoltageforum.net/index.php?topic=123.0
- Frequency drop measurement (topic 701): https://highvoltageforum.net/index.php?topic=701.0
- Fat Coil QCW (TCML): https://www.pupman.com/listarchives/2014/Nov/msg00064.php
- Understanding DRSSTC (TCML): https://www.pupman.com/listarchives/2013/Feb/msg00052.html