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Shaping of optical surfaces by ion beams
Vacuum
news
Controls comprise a single switch to control pumpdown and air admittance, and 2 push buttons for plating. Large pump capacities (600 litre/second diffusion pump and 320 litre/minute 2 stage rotary pump) with high conductance valving allow pumpdown to plating pressures in under 20 seconds. On completion of plating, the unit air admits in under 3 seconds. Instrumentation for operation comprise vacuum gauge and ammeter, which are situated in a conveniently located 19 inch rack. In addition, 2 blank panels are fitted to the console for instrumentation if required. All non-essential controls and indicator lights are mounted on a swing out panel on one side of the operator. In addition to the standard OC41300. Dynavac have recently manufactured and sunnlied six OC41300 final freauencv plat-ers fitted w:th ‘integral cold wilding facilities. These are presently being used for producing high stability close tolerance crystals with exceptionally low rejection rates and reduced p;oducti& times. Dynavac High Vacuum Ptv Ltd C&Ie numb& 32 on Reade; Enquiry Service card
Shaping of optical surfaces by ion beams A new accelerator from Edwards High Vacuum International is being used to work optical materials by ion beams at the National Physical Laboratory. The ultimate aim is to develop a shaping technique which is more precise and controllable than conventional glassworking, especially when complex surface shapes are required. The low energy (5-30 keV) accelerator was built by the Ion Beam Group in Edwards’ Central Research Laboratory, which is carrying out a development programme on heavy ion beam systems. Beams of heavy rare gas ions at current densities up to 1 mA/cm” will be used to sputter-machine the surfaces of optical materials, over an area of 40 mm diameter. This work requires that the vacuum system and pumping equipment operate under very clean conditions. Argon ions are produced in an If source and accelerated through an electrode lens, giving a beam with an ion current up to 40 PA. The beam is passed through a magnetic mass-energy analyzer, which has three exit ports providing for zero and 30” positive or negative deflection. For operating convenience, the ion source is at high tension and the magnet and target chamber are at earth potential. Ion beam equipment is custom built by Edwards Ion Beam Grouw. which works in consultation with the Iok Effects Group of AWRE, Aldermaston. Current projects include construction of a 150 keV accelerator, financed by the Central R & D Group of BOC. Edwards High Vacuum Int Circle number 33 on Reader Enquiry Service card 20
New accelerator
from
Edwards
High
Vacuum
High-voltage coaxial cable for vacuum chambers Ceramaseal, Inc has introduced a line of in-vacuum bakeable coaxial cables which in recent tests have proven unusually suitable for signal lead shielding at potkntials uw to 4 kV dc. The company believes this is the first commerciall; available highvoltage coaxial cable which meets the requirements of ultrahigh vacuum work.
Bakeout capability is 450 C, achieved by avoiding organic insulating materials. All materials used in the cables-and connectors are non-magnetic. The OFHC cowwer conductors in Fhe cable are surrouided by a series of nested, electronic-grade steatite insulating rings. The rings are encased in a shielding medium of braided stainless steel. Preliminary test reports have indicated no measurable leakage current at voltages to
news
Controls comprise a single switch to control pumpdown and air admittance, and 2 push buttons for plating. Large pump capacities (600 litre/second diffusion pump and 320 litre/minute 2 stage rotary pump) with high conductance valving allow pumpdown to plating pressures in under 20 seconds. On completion of plating, the unit air admits in under 3 seconds. Instrumentation for operation comprise vacuum gauge and ammeter, which are situated in a conveniently located 19 inch rack. In addition, 2 blank panels are fitted to the console for instrumentation if required. All non-essential controls and indicator lights are mounted on a swing out panel on one side of the operator. In addition to the standard OC41300. Dynavac have recently manufactured and sunnlied six OC41300 final freauencv plat-ers fitted w:th ‘integral cold wilding facilities. These are presently being used for producing high stability close tolerance crystals with exceptionally low rejection rates and reduced p;oducti& times. Dynavac High Vacuum Ptv Ltd C&Ie numb& 32 on Reade; Enquiry Service card
Shaping of optical surfaces by ion beams A new accelerator from Edwards High Vacuum International is being used to work optical materials by ion beams at the National Physical Laboratory. The ultimate aim is to develop a shaping technique which is more precise and controllable than conventional glassworking, especially when complex surface shapes are required. The low energy (5-30 keV) accelerator was built by the Ion Beam Group in Edwards’ Central Research Laboratory, which is carrying out a development programme on heavy ion beam systems. Beams of heavy rare gas ions at current densities up to 1 mA/cm” will be used to sputter-machine the surfaces of optical materials, over an area of 40 mm diameter. This work requires that the vacuum system and pumping equipment operate under very clean conditions. Argon ions are produced in an If source and accelerated through an electrode lens, giving a beam with an ion current up to 40 PA. The beam is passed through a magnetic mass-energy analyzer, which has three exit ports providing for zero and 30” positive or negative deflection. For operating convenience, the ion source is at high tension and the magnet and target chamber are at earth potential. Ion beam equipment is custom built by Edwards Ion Beam Grouw. which works in consultation with the Iok Effects Group of AWRE, Aldermaston. Current projects include construction of a 150 keV accelerator, financed by the Central R & D Group of BOC. Edwards High Vacuum Int Circle number 33 on Reader Enquiry Service card 20
New accelerator
from
Edwards
High
Vacuum
High-voltage coaxial cable for vacuum chambers Ceramaseal, Inc has introduced a line of in-vacuum bakeable coaxial cables which in recent tests have proven unusually suitable for signal lead shielding at potkntials uw to 4 kV dc. The company believes this is the first commerciall; available highvoltage coaxial cable which meets the requirements of ultrahigh vacuum work.
Bakeout capability is 450 C, achieved by avoiding organic insulating materials. All materials used in the cables-and connectors are non-magnetic. The OFHC cowwer conductors in Fhe cable are surrouided by a series of nested, electronic-grade steatite insulating rings. The rings are encased in a shielding medium of braided stainless steel. Preliminary test reports have indicated no measurable leakage current at voltages to