Difference between revisions of "Ion Optics"
From CASE
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| + | ==Background== | ||
Students interested in Ion Optics should consider taking Phy 684 which is often a course in Accelerator Physics taught by CASE faculty. | Students interested in Ion Optics should consider taking Phy 684 which is often a course in Accelerator Physics taught by CASE faculty. | ||
A nice primer oriented to low energy facilities was posted to the web by Dr. Berg of Notre Dame University at [http://www.nd.edu/~nsl/Lectures/IonOpticsClass/index.htm Intro to Ion Optics] | A nice primer oriented to low energy facilities was posted to the web by Dr. Berg of Notre Dame University at [http://www.nd.edu/~nsl/Lectures/IonOpticsClass/index.htm Intro to Ion Optics] | ||
| − | ===The NSL Facility=== | + | ==Particulars== |
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| + | ====The NSL Facility==== | ||
* Negative ions sputter from the source sample holder (often called "cone" locally). Details of the electric field lines, production of a conical divot and material all contribute to the emittance of the ions as they leave the sample holder. Typical units are tens of MeV-mm/mradian | * Negative ions sputter from the source sample holder (often called "cone" locally). Details of the electric field lines, production of a conical divot and material all contribute to the emittance of the ions as they leave the sample holder. Typical units are tens of MeV-mm/mradian | ||
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* The Beamline Quadrupole creates a focus at the target. If steering is required there are horizontal and vertical steerers on each beamline | * The Beamline Quadrupole creates a focus at the target. If steering is required there are horizontal and vertical steerers on each beamline | ||
| − | === Glossary of Ion Transport Terms === | + | ==== Glossary of Ion Transport Terms ==== |
Here is a link to a glossary of terms used in beam transport at facilities such as the CASE Tandem Van de Graaff [[IonTransportGlossary]] | Here is a link to a glossary of terms used in beam transport at facilities such as the CASE Tandem Van de Graaff [[IonTransportGlossary]] | ||
Revision as of 10:16, 26 August 2010
Background
Students interested in Ion Optics should consider taking Phy 684 which is often a course in Accelerator Physics taught by CASE faculty.
A nice primer oriented to low energy facilities was posted to the web by Dr. Berg of Notre Dame University at Intro to Ion Optics
Particulars
The NSL Facility
- Negative ions sputter from the source sample holder (often called "cone" locally). Details of the electric field lines, production of a conical divot and material all contribute to the emittance of the ions as they leave the sample holder. Typical units are tens of MeV-mm/mradian
- The electric field created by the extraction electrode "extracts" the negative ions.
- A gridded Einzel Lens focuses the beam to the object point of the inflection magnet. An aperture is placed where the beam is large to allow for reduced currents.
- The 90 degree inflection magnet has a natural focal length of R (radius= ?? meters). This matched in the vertical plane by shaped pole pieces.
- An aperture at the entrance to the injector accelerator tube reduces the electron load to the tube and provides an image to the lens of the tube. This lens is weak.
- An electrostatic triplet and electrostatic steerer at Ground Station create a beam waist just in front of the Tandem, matching to the bulge lens effect of the Tandem accelerator tubes.
- The first 20 planes of the Low Energy column have reduced value (gradually decreasing from full to half value) to weaken the bulge lens effect.
- There are no active optical elements in the Tandem Van de Graaff, only gently focusing via the spiral inclined electrodes in the tubes
- The High Energy AG Lens is the first magnetic focusing element. It works with the HE Magnetic Steerer to create a beam waist at the object point of the Analyzing Magnet. We create this with a circular aperture ~ 1.5 meters in front of the magnet.
- Image #2 is the image point of the Analyzer. It is closer to the magnet than the object point, therefore we have magnification of less than one.
- The Tunnel Triplet has its object point at Image 2. Along with the Tunnel vertical steerer and the Switching Magnet is creates an image on whatever beamline is selected.
- The Beamline Quadrupole creates a focus at the target. If steering is required there are horizontal and vertical steerers on each beamline
Glossary of Ion Transport Terms
Here is a link to a glossary of terms used in beam transport at facilities such as the CASE Tandem Van de Graaff IonTransportGlossary
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