Beam Imaging Solutions (BIS) presents the new model RFIS-100 ion source assembly. The RFIS-100 is designed to be retrofittable to the standard model G-1 and G-2 ion gun accelerator systems. The ion source operates with a RF power supply at 13.56 MHz with manual adjust match network to produce an inductively coupled plasma (ICP). The RF ion source offers many benefits over the standard Colutron hot cathode DC discharge source including much longer operating time between maintenance, especially with oxygen and reactive gasses, and also higher beam currents.
Beam Imaging Solutions (BIS) presents the new model RFIS-100 ion source assembly. The RFIS-100 is designed to be retrofittable to the standard model G-1 and G-2 ion gun accelerator systems. The ion source operates with a RF power supply at 13.56 MHz with manual adjust match network to produce an inductively coupled plasma (ICP). The RF ion source offers many benefits over the standard Colutron hot cathode DC discharge source including much longer operating time between maintenance, especially with oxygen and reactive gasses, and also higher beam currents. In addition to being able to produce ions from gasses, the new ion source has the added capability of producing metal ions by sputtering the source gas with a metal target in the discharge chamber. Customers that do not already own a Colutron ion gun can purchase the new source to fit to their own ion accelerator systems. Customers that have the Colutron ion gun would remove the standard Colutron DC ion source and heat sink assembly from the ion gun and attach the RF ion source directly to the Colutron model 500 insulator flange. The RF source does not require the Colutron heat sink to operate.
Ion Source Components
RFIS-101 Ion Source Assembly
RFIS-100 with Shield
RFIS-100 with Match Network
Composition
1. RFIS-101 Ion Source Assembly (See picture above). To minimize down time, a fresh RFIS-101 assembly can be switched out very quickly with a used unit that might require cleaning and/or servicing.
2. RFIS-007 Ion Source Flange. The source flange has two VCR water feedthrough connections for the RF antenna, and 50 ohm BNC connection for an optional sputter target connection, as well as a 12kV high voltage feedthrough for an electric start circuit.
3. RFIS-010 Gas Isolator. To prevent the plasma from shorting to the ion source flange, a specially designed high voltage gas break has been utilized allowing up to 10kV isolation. The gas isolator is attached to the RFIS-007 ion source flange via a 1/8″ swagelok fitting.
3. RFMB-100 MRF Match Box. The RF Match box houses the high current and high voltage vacuum variable capacitors needed for proper tuning of the RF antenna, as well as gas, water and electrical connections required for source operation. The match box also houses the new high voltage arc supply for simple electric push button starting of the ion source plasma.
4. RFMB-200 High Voltage Safety Enclosure. The RFIS-100 package also includes a plexiglas enclosure to ensure operator safety during high voltage operation of the ion source. A fan is incorporated into the enclosure to provide additional cooling of the ion source.
Technical Information
Ion Source Flange
6” (152mm) Conflat
RF Power Supply
13.56MHz, 500W
Sputter Target, Metal Ions (Optional)
200V, 0.5A
RF Antenna
6.5 Turn, 2mm diameter Cu tube, water cooled, 1/8″ VCR
Gas Isolator
10kV Isolation, 1/8” Swagelok input
RF Antenna Feedthrough
5kV Isolation, Copper, 1/8″ VCR
Plasma Start Circuit
12kV Isolation feedthrough
Water Cooling Requirement
1 Liter/min (RF Antenna)
Force Air Cooling Requirement
Fan built into Plexiglas Enclosure for High Voltage Safety protection. (Fan Specification:47 CFM, 12VDC, 200mA)
The RFIS-100 was tested at a customer site with a Colutron model G-2 ion gun system. The ion source was run at 1, 3, 6, and 9 keV with neon, helium, and argon. The output ion beam currents were compared with a standard Colutron model 100 ion source operating with the same gasses at the same beam potentials. On average, it was found that the ion beam current levels were between 3 – 8 times higher operating with the RF-100 source when compared to the standard Colutron source. Below is a chart showing 9keV He+ ion beam current collected in a 2.5cm diameter Faraday cup located 44cm from the exit of the ion gun for both the RF-100 and Colutron model 100 DC filament source. The ion current is recorded versus RF power for the RF ion source, and anode discharge current for the Colutron source. For the complete data package in MS Excel, please contact Dr. Erik Wåhlin at [email protected].
Metal Ion Beams by Sputtering (Optional)
RFIS-100 Ion Source Sputter Targets (Ni, Cu, Al)
Pure metal sputter targets are available as an option for the production of metal ions. The cylindrical shaped target is placed inside the discharge chamber and sputtered by ions from a support gas, typically argon. To control the ion output, the target is electrically biased negative to increase the support gas positive ion sputter rate. The experimental plot below shows an approximate linear increase in 3keV Nickel metal ion output vs. applied target bias voltage. The Beam Imaging Solutions FC-1 Faraday cup used for current measurements has a 0.25” OD aperture and was located about 30” from the exit of the ion gun.
Optional Equipment
RF-100 Power Supply Unit for Colutron Model E-1 and E-2 Control Units
The model RF-100 Power Supply unit is available for the RFIS-100 ion sources. The power supply unit is made to replace the Colutron DC ion source power supplies (anode, filament) for customers who have a Colutron model E-1 or E-2 ion gun controller and are converting their system to operation with the RFIS-100 ion source. Like the standard Colutron DC (filament) ion source power supplies, which are mounted in an plexiglas enclosure for operation to 10kV, the new RF-100 power supply system is also isolated for operating beams up to 20kV. The power supply fits into the same slot on the Colutron E-1 and E-2 control units. The RF-100 also includes ion source cable and digital thermocouple gauge for monitoring ion source pressure.
Model CU-1 Cooling Unit for RFIS-100 Ion Source
A closed cycle cooling unit for the model RFIS-100 ion source is now available.
The CU-1 cooling unit utilizes a non-conductive refrigerant (HFC-134a) which allows the ion source to be floated to at least 20kV. The cooling system uses a 1/4 horse power high temperature condensing unit to remove heat dissipated by the ion source. A liquid and gas mix of the refrigerant HFC-134a is pressurized by the compressor and is circulated through the ion source. The refrigerant is returned via the low pressure side of the compressor and heat from the refrigerant is removed from a fan blown condensing coil and then stored in a storage tank. The temperature of the returning refrigerant from the ion source is monitored via a temperature sensor that is attached to the return (suction) side. The cooling unit does not require an expansion valve to operate properly. A pressure switch is installed on the high pressure side of the compressor and will shut off the pump if the compressor pressure exceeds 175 psi. Low and high pressure gauges are included to monitor proper operation of the cooling unit, along with high pressure refrigeration hoses for connection to the RFIS-100 ion source.
