Hi Dex,Your question is good, but it is based on the assumption that potential voltage equals a given spark length. This isn't the case in a Tesla coil output spark like it is in the potential required for 2 bodies of some size and geometry to arc to one-another. Over and over again it's been shown that spark "lengths" in TC service follow a power curve. It depends on the power delivered to the streamers and time. The actual voltage at the top load cannot be directly linked to spark length without the inclusion of the change in current over time. The main parameters that supply this are the inductances, capacitances, power supply, and top load limit on voltage.
A better question and answerable question is what is the approximate max spark length possible for a given power. Then we can easily quote John Freau's 1.7 x sqrt(input watts) spark length equation which has held well for more than a decade. There are certainly situations which affect even this spark length, but it is the most accurate equation for spark lengths over the spectrum of variations with systems.
I can accurately say that if you used 100kV, 200kV, 300kV and kept power unchanged, then for a 1000W coil, expect the following ideally.
1) 100kV = 53.7" 2) 200kV = 53.7" 3) 300kV = 53.7"This is not a trick. It states that the terminal voltage is not affecting the spark length directly. Maintaining power delivered to the spark at 1000W, the current is adjusting (10mA, 5mA, 3.3mA). However, if you were to double the power to 2000W, then (ideally):
1) 100kV = 76" 2) 200kV = 76" 3) 300kV = 76"Note the spark length increased only by a ratio of 76/53.7 for twice the power. This is the reality of Tesla Coils. BTW, by "ideally" I'm referring to the fact that not all coils will achieve the spark lengths for the power given. Most will be below this length, some at this length, and a select few a little better (John's system during these tests were quite efficient).
Another reality not thought about is that you will be hard-pressed to keep the top terminal below 100kV and above 400kV. The top terminal limits voltage but can also break out at peak voltages which are far from average voltages. From a completely academic standpoint, it's fine to contemplate the top terminal voltage, but for breakout, consider the peak voltage the top terminal will see (punching out). However, after the initial breakout, the current delivered to the streamer is what will dictate to some degree the spark lengths achievable. The power is what pumps the current into the spark channel (and the more power, the longer and higher the current is available).
I can probably speak for a lot of coilers when I say that reducing gap losses (more power delivered in the emf at the primary and thus the secondary) and more power in the supply itself is what has increased spark lengths on any given coil. There is of course secondary inductances better equipped than others at delivering the power to the top terminal and the terminal C itself determining when breakdown occurs, but it is "power" that ultimately delivers short or long sparks (power is the predominant player with spark lengths).
Take care, Bart Dex Dexter wrote:
I have a good question I don't know answer to. QUESTION: What is aproximately maximum spark lenght possible for a given output voltage Tesla system generates?Regardless of the efficiency,how long spark can be produced by a Tesla-type impulsive devices with voltage levels:1) 100 kV 2) 200 kV 3) 300 kVCan a high power impulse source,like a Tesla transformer,put out a 10 feet long spark with 'only' 100 kV voltage peaks?To accomplish that it is free to use any power input level,any size and shape of a terminal capacity,any firing rate wanted,andthe best high frequency excitation waves mix.DRSSTC,VTTC,etc. The only limiting thing is not to exceed 100 000 V terminal potential. Supposing a normal atmosphere enviroment is that possible? I know that in no circumstance 50 kV can close 5' wide gap unless directly conducting path is formed somehow,or astrong external ionization occurs ,like exposure to a flame,extremely powerful lasers,but Tesla transformers are the champs of 'spark pumping' and I was wondering what could be done with 100 kV.Thanks for your answers and explanations.Dex_____________________________________________________________ Washington DC's Largest FREE Email service. ---> http://www.DCemail.com ---> A Washington Online Community Member ---> http://www.DCpages.com _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla