I'm sure you know this interesting decoration in recent years widely sold.
You can also build a simple plasma globe yourself.
The basis of plasma ball is a small source of high frequency high voltage of several thousand volts at a frequency of several to several tens of
kilohertz. This voltage is fed to the electrode placed in the center of a glass sphere
filled with a suitable gas. Due to the capacitive currents, discharges are formed between the electrode and glass.
When you touch the ball the glowing discharges will point mostly to the area where you touch.
In my design, the high frequency high voltage supply is very simple. It is using the HV transformer from an old television receiver. It must be a transformer without integral rectifier, to be able to provide a high frequency voltage. The transformer primary winding is removed or left unused and a new primary is wound (5 turns and 3 turns) as shown in schematic below. The secondary winding is left in original state. Another part of the circuit is power transistor and a small bulb (24V 5 to 10W) serving as resistance and simultaneously signaling the power on (this bulb can be replaced by a resistor of 50-100 Ohm 5-10 W). These components form a simple oscillator. 1000uF capacitor only reduces the internal resistance of the power supply. Voltage is about to 16kV and frequency around 25kHz. Note - the negative pole must be grounded.
The plasma ball is replaced with an ordinary mains voltage light bulb (cca 25 - 200W), which is filled with argon. The effect is similar. Between the filament and the bulb several moving sparks are formed.