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An external gas supply system for a Van De Graaff positive ion accelerator
Nuclear Instruments and Methods in Physics Research B40/41 North-Holland, Amsterdam
AN EXTERNAL L.A.
1069
(1989) 1069-1070
GAS SUPPLY SYSTEM FOR A VAN DE GRAAFF POSITIVE ION ACCELERATOR
RAYBURN
Department
of Physics, The University of Texas at Arlington,
Arlington,
Texas 76019, USA
A simple system, which allows an ion source gas bottle (located in the terminal of the accelerator) to be pressurized through copper and polypropylene tubing from an external gas cylinder, is described. Since it is not necessary to remove the insulating gas from the accelerator tank, a complete change in accelerated ions can be made in 30 min or less. Electrical breakdowns in the polypropylene tubing (with subsequent rupture) is prevented by backfilling with insulating gas.
1. Introduction
pressure-seal
the hole in the accelerator base (fig. 1). to a Plexiglas control rod which allowed the manual operation of a Hoke needle valve (with a slip-clutch)located in the gas line to a small (500 cm3) gas storage bottle mounted in the terminal. Pressure in the rf ion bottle was controlled by a thermo-mechanical leak (obtained from High Voltage Engineering Corporation). Typical operation of the system consisted of the following steps: (a) the entire system was evacuated (to less than 5 pm pressure), (b) the terminal gas bottle was filled to approximately 70-100 lb/in* pressure at which point the control rod was used to close the valve on the bottle, (c) the valve to the source of gas was closed and the remainder of the system evacuated to a pressure of a few microns, (d) the section of line containing the polypropylene tubing was isolated by closing the valve to the right of the pressure gauge and then was filled with insulating gas by opening the adjacent valve. BackThe brass
One of the time-consuming problems associated with of our 2 MV Van de Graaff positive ion accelerator was that of changing the accelerated ion species. Typically it would require approximately 12 to 24 h for a change to an ion different from the usual H+ and He+ obtainable from the two gas storage bottles in our terminal. We describe a simple system which allows a change of accelerated ion in 30 min or less. the operation
2. Experimental
The high voltage bushing (not needed for the positive ion mode of operation) on the accelerator base was removed. This made available a 2; in. opening. Two $ in. copper tubes and a brass rod (with pressure seal) were fitted on a metal plate which then was used to
rod was coupled
Polypropylene Tubing
I
in Terminal
SOlNIX of Gas
Fig.
r30nk
Base Of ACCderat0r Tank
1. External gas system for Van de Graaff accelerator. Valves (Hoke $ in.) are indicated by a cross within a circle. All tubing is copper except for one piece of polypropylene (; in.) that runs parallel to the accelerator column.
0168-583X/89/$03.50
(North-Holland
0 Elsevier Science Publishers Physics Publishing Division)
B.V.
VII. ACCELERATOR
TECHNOLOGY
1070
L.A. Rayburn / External gas supply system for Van de Graaff
Table 1 Gases used
Ions accelerated
Hydrogen Deuterium Helium Nitrogen Oxygen Neon Argon Sulfur hexafluoride
H+, H; Df He+ N+, N; o+, 0: Ne+ Ar+ s+, (SF)+
filling with downs with tubing.
insulating subsequent
gas prevents electrical breakrupture of the polypropylene
3. Results We have used the gases listed in table 1 with our rf ion source and accelerated the indicated ions. I am indebted to Professor F.D. McDaniel for a description of the system in use at The University of North Texas.
AN EXTERNAL L.A.
1069
(1989) 1069-1070
GAS SUPPLY SYSTEM FOR A VAN DE GRAAFF POSITIVE ION ACCELERATOR
RAYBURN
Department
of Physics, The University of Texas at Arlington,
Arlington,
Texas 76019, USA
A simple system, which allows an ion source gas bottle (located in the terminal of the accelerator) to be pressurized through copper and polypropylene tubing from an external gas cylinder, is described. Since it is not necessary to remove the insulating gas from the accelerator tank, a complete change in accelerated ions can be made in 30 min or less. Electrical breakdowns in the polypropylene tubing (with subsequent rupture) is prevented by backfilling with insulating gas.
1. Introduction
pressure-seal
the hole in the accelerator base (fig. 1). to a Plexiglas control rod which allowed the manual operation of a Hoke needle valve (with a slip-clutch)located in the gas line to a small (500 cm3) gas storage bottle mounted in the terminal. Pressure in the rf ion bottle was controlled by a thermo-mechanical leak (obtained from High Voltage Engineering Corporation). Typical operation of the system consisted of the following steps: (a) the entire system was evacuated (to less than 5 pm pressure), (b) the terminal gas bottle was filled to approximately 70-100 lb/in* pressure at which point the control rod was used to close the valve on the bottle, (c) the valve to the source of gas was closed and the remainder of the system evacuated to a pressure of a few microns, (d) the section of line containing the polypropylene tubing was isolated by closing the valve to the right of the pressure gauge and then was filled with insulating gas by opening the adjacent valve. BackThe brass
One of the time-consuming problems associated with of our 2 MV Van de Graaff positive ion accelerator was that of changing the accelerated ion species. Typically it would require approximately 12 to 24 h for a change to an ion different from the usual H+ and He+ obtainable from the two gas storage bottles in our terminal. We describe a simple system which allows a change of accelerated ion in 30 min or less. the operation
2. Experimental
The high voltage bushing (not needed for the positive ion mode of operation) on the accelerator base was removed. This made available a 2; in. opening. Two $ in. copper tubes and a brass rod (with pressure seal) were fitted on a metal plate which then was used to
rod was coupled
Polypropylene Tubing
I
in Terminal
SOlNIX of Gas
Fig.
r30nk
Base Of ACCderat0r Tank
1. External gas system for Van de Graaff accelerator. Valves (Hoke $ in.) are indicated by a cross within a circle. All tubing is copper except for one piece of polypropylene (; in.) that runs parallel to the accelerator column.
0168-583X/89/$03.50
(North-Holland
0 Elsevier Science Publishers Physics Publishing Division)
B.V.
VII. ACCELERATOR
TECHNOLOGY
1070
L.A. Rayburn / External gas supply system for Van de Graaff
Table 1 Gases used
Ions accelerated
Hydrogen Deuterium Helium Nitrogen Oxygen Neon Argon Sulfur hexafluoride
H+, H; Df He+ N+, N; o+, 0: Ne+ Ar+ s+, (SF)+
filling with downs with tubing.
insulating subsequent
gas prevents electrical breakrupture of the polypropylene
3. Results We have used the gases listed in table 1 with our rf ion source and accelerated the indicated ions. I am indebted to Professor F.D. McDaniel for a description of the system in use at The University of North Texas.