Beam Current Density as a function of Beam Energy

• Magnetron Power 280W
• Chamber Pressure 8x10^-4Torr. Pumping Speed 200l/s
• Gas: Nitrogen
• Extractor Voltage: 500V
• Measured at 100mm from grids
• Focused molybdenum grids with 120mm focal point. 2.0mm screen 1.6mm extractor hole diameter

Beam Current Density as a function of Plasma Pressure

As the gas flow through the source is reduced the plasma pressure falls along with the pressure in the chamber. As chamber pressure is easily measured, this is the parameter plotted. Gas flow can be calculated using the known pumping speed. e.g. 8x10^-4 Torr is equivalent to a gas flow of 13sccm. As the plasma pressure reduces the ionisation efficiency increases and the extracted ion current rises.

• Magnetron Power 280W
• Pumping Speed 200l/s
• Gas: Nitrogen
• Anode Voltage: 250V
• Extractor Voltage: 400V
• Measured at 100mm from grids
• Focused molybdenum grids with 120mm focal point

Beam Current Density as a function of Magnetron Power

From the graph below it can be seen that extracted ion current is approximately linear with applied microwave power.

• Magnetron Power 280W
• Pumping Speed 200l/s
• Gas: Nitrogen
• Anode Voltage: 250V
• Extractor Voltage: 400V
• Measured at 100mm from grids
• Focused molybdenum grids with 120mm focal point

Beam Current Density as a function of Anode and Extractor Voltages

The beam current density was measured as a function of Anode (screen grid) and extraction grid voltages.

• Magnetron Power 280W
• Chamber Pressure 9.8x10^-4 Torr. Pumping Speed 200l/s
• Gas: Nitrogen
• Measured at 100mm from grids
• Focused molybdenum grids with 120mm focal point. 2.0mm screen 1.6mm extractor hole diameter

Beam Current Density as a function of Extractor Voltage

• Magnetron Power 280W
• Chamber Pressure 9.8x10^-4 Torr. Pumping Speed 200l/s
• Gas: Nitrogen
• Anode Voltage: 100V
• Measured at 100mm from grids
• Focused molybdenum grids with 120mm focal point