Used a schematic of a medium small size Tesla coil with all parameters:

L1=7uH

C1=200nf

L2=72mH

C2=15pf

DC bus 5000V

Every running simulating this schematic one time we can get many information of a spark gape tesla coil (SGTC) by hanging the marker probe at any test point in the circuit, for example V,I,W. . .

Figuer1: schematic equivalent circuit of a SGTC

*Switch U1represent the charge circuit for C2

*Switch U2disconect the oscillation circuit with the charger circuit while the coil works.

*Switch U3 represents the spark gape

*R2 equivalent resistor of spark of the gape

*R3 equivalent resistor of spark at toroid

Result

Voltage

Figure2: voltage wave form at L1.Base on it we can determine dynamic primary resonance frequency Fd1=. . . . (in coupled)

Figure3: voltage waveform at L2. Base on it we can determine dynamic secondary resonance frequency Fd2= . . . (in coupled)

We will see the dynamic frequencies are floating and change by the K and load resistor R3that reflect the situation of the spark (heavy or light)

By formula we can calculate static primary resonance frequency Fs1=134.5 kHz

And static secondary resonance frequency Fs2=153.1 kHz

Current

Figure 4: is primary current wave that created by capacitor C2 discharge all its electrostatic emery in halt cycle to L1 as power pack1 and then going back from L1 and forth to C1 become power pack2; power pack3; power pack4; power pack5 from 11us to 32us, they gradually become smaller. This action transfer energy from primary to secondary coil form the ring up wave continue in 6 cycle until 63uswith the amplitude 150kV peak max in figure 3. (Remember that energy transfer by current and magnetic field from primary coil to secondary coil)

We see the V gain factor =√(L2/L1)=30

So the max. peak output voltage =150KV

Power

Figure 5: in primary a halt red cycle

WC2=1/2 V^2 C=2.5Joule (all the power in C2 is only 45% of this because loss 55% in the spark gap or much more if resistor of the gap >1 ohm?)

Figure 6: energy transfer from primary to secondary in the case K=.5 and in the case K=.15 (this figure show K=.15K=.2 is the best)

Figure 7: power in primary coil (peak power 1.7Mw)+ power in secondary coil (peak power 200Kw)

Figure 8: power in the spark (peak power 54Kw)

And some data more

The equivalent resistor R3 is important if its values only 1 ohm the efficiency of the coil drop 50% approx.

This information s shows us very clearly how the SGTC work. Especially it indicates the static resonance frequency (independent resonance frequency) and dynamic resonance frequency (resonance frequency in coupled) here we identify 2frequencies are constant and 2 other are float while running in a tesla coils.

With the patient and meticulous analyses this tool can help us a lot for design and tuning the coil.

This tool also leads me to another tool can helpful for DRSSTC. I will introduce that tool in a new topic.