cathode spot

By not allowing the cathode spot to remain in one position too long aluminium targets can be used and the number of droplets is reduced.

This process can create an incandescent cathode spot which frees more particles, thereby sustaining the arc.

The cathode spot is only active for a short period of time, then it self-extinguishes and re-ignites in a new area close to the previous crater.

Observations of current sheet velocity were interpreted as evaporation of cathode material from cathode spots.

Combined steered arc / unbalanced magnetron cathode with modulated cathode spot confinement zone.

Cold electrodes can also spontaneously produce electron clouds via thermionic emission when small incandescent regions (called cathode spots or anode spots) are formed.

Since momentary interruptions or reductions of output current may cause the cathode spot to extinguish, many rectifiers incorporate an additional electrode to maintain an arc whenever the plant is in use.

One downside of the arc evaporation process is that if the cathode spot stays at an evaporative point for too long it can eject a large amount of macro-particles or droplets.

Ectons occur in plasma-involving phenomena, such as: electrical discharges in vacuum, cathode spots of vacuum arcs, volumetric discharges in gases, pseudosparks, coronas, unipolar arcs, etc.

The localised temperature at the cathode spot is extremely high (around 15000 C), which results in a high velocity (10 km/s) jet of vapourised cathode material, leaving a crater behind on the cathode surface.

Worse still if the cathode target material has a low melting point such as aluminium the cathode spot can evaporate through the target resulting in either the target backing plate material being evaporated or cooling water entering the chamber.

Chinese cathode spot premia have fallen for three consecutive weeks from the $130-$180/t level to $100-$130/t in the first week of June. • LME open interest has fallen substantially in the last week alongside lower prices suggesting longs have been liquidated.

The arc evaporation process begins with the striking of a high current, low voltage arc on the surface of a cathode (known as the target) that gives rise to a small (usually a few micrometres wide), highly energetic emitting area known as a cathode spot.