The lowest voltage at which a spark occurs depends, among other things, on the width if the spark gap. You could probably get a spark at 50 volts or lower with a very small gap.

1000volt is a lethal.. Maybe i should use a gas which has lower dielectric breakdown so i can use the 220volts from mains.

1000volt is a lethal.. Maybe i should use a gas which has lower dielectric breakdown so i can use the 220volts from mains.

Good luck to you in your lowpower TC quest! I'm doing the same, but I may be a bit farther along, so I hope you dont' mind my sharing my experience.

A Telsa Coil by definition involves High Voltage in the secondary resonator. You will not get corona or sparks unless you exceed 20 kV at least, although a small arc can form at very short distances at 6 kV or so.

Microcontroller is right about the voltage, the current and the frequency of the secondary output from a Tesla Coil. The true HV from the resonator, if it's working right, is perfectly safe as long as you don't let the actual arc touch your skin directly. Use a firm grip on a wrench or screwdriver and take the spark/arc to the metal, this will prevent you from getting a painful RF burn from the arc itself.

There are three major types of Tesla Coil: the Spark Gap  and the Vacuum Tube and the Solid State types.
They all use some strategy to make pulses in a Primary Coil, which then causes the Secondary Coil to ring like a bell -- at radio frequencies which were considered high in Tesla's day but now are merely considered relatively low frequency, between 300 kHz and 3 or 4 MHz.

The main differences in TC types are in how the Primary Pulses are made. The coils themselves are generally pretty much the same between types, with some peculiarities in style and coupling.

The Spark Gap Tesla Coil (SGTC) uses DANGEROUS HIGH VOLTAGE in the Primary Coil and power supply, and a Spark Gap/Capacitor combination to make the primary pulsations. IT IS A DANGEROUS SYSTEM for beginners to work with for that reason, although it is the very simplest form of the Tesla Coil and is what Tesla himself used. You will need at least 6,000 volts to get good sparks in your spark gap, which is how the secondary is "struck" to make it ring.

The VTTC is less dangerous but much more complicated and also not for the beginner.

The Solid State Tesla Coil is somewhat complicated to construct but is the safest by far as it does NOT involve high voltage in the Primary Power Supply.

I have recently been working on a "Class E" SSTC, a single-mosfet oscillator running in the very efficient Class E mode, driving a 5 turn primary on a table top resonator. I am developing this coil as a demonstrator, and I'm currently running it on 48 volts input from 4 12volt batteries, but I intend to run it directly from the mains eventually when it's fully tuned and modulated.

I have also developed a much more powerful SSTC using a full bridge mosfet power stage that operates on direct mains power, but it's a bit more dangerous in it primary... but 170 volts and no spark gap is still much much safer than even my smallest Neon Sign Transformer powered coil running at 6 kV 30mA with a rotary spark gap.

The photos below are from the ClassE coil, showing the corona and the basic layout. This is at 48 volts input to the system, the single mosfet IRFP450 oscillating in Class E mode.