Ion wind
Ion wind, also known as electric wind or corona wind, is a flow of gas created by the momentum transfer of ions to neutral gas molecules. This phenomenon occurs when a strong electric field is generated near a sharp electrode, causing ionization of the surrounding gas.
The process typically begins with a high voltage applied to a sharp electrode, such as a needle or thin wire. The strong electric field near the electrode causes electrons to be stripped from neutral gas molecules (often air), creating positive ions. These ions are then accelerated by the electric field towards an electrode of opposite polarity.
As the ions move through the gas, they collide with neutral gas molecules. These collisions transfer momentum from the ions to the neutral molecules, causing the neutral molecules to move in the same direction as the ions. This movement of neutral gas molecules constitutes the ion wind.
The strength of the ion wind depends on several factors, including the voltage applied to the electrodes, the geometry of the electrodes, the pressure and composition of the surrounding gas, and the distance between the electrodes. Higher voltages and sharper electrodes generally produce stronger electric fields and thus stronger ion winds.
Ion wind has various applications, including:
- Electrostatic precipitators: Used to remove particulate matter from exhaust gases.
- Electronic cooling: Employed to cool electronic components by convective heat transfer.
- Microfluidic devices: Utilized to manipulate and transport fluids at the microscale.
- Thrust generation: Researched for potential use in electric propulsion systems for spacecraft.
The effect is distinct from other phenomena like dielectric breakdown or spark formation, although these phenomena can occur alongside ion wind under specific conditions. Ion wind relies on continuous, but relatively low-energy, ionization of the gas rather than a sudden, catastrophic discharge.