Ion Source Classification
How different ion sources generate characteristic ion species and how they are grouped by operating regime.
Overview
Ion sources are classified by their ionization mechanism and operating pressure. Common groupings include electron impact / gas discharge sources (EI, CI, SNICS), plasma sources (ECR, EBIS/EBIT), and atmospheric-pressure soft ionization sources (ESI, APCI, MALDI). Each source type tends to favor certain ion species (molecular ions, protonated ions, negative ions, metal clusters, etc.).
Below are the ion species pages, which describe typical beam currents, source types, and target materials for each ion.
Ion species reference
Light Ions Z ≤ 14
Hydrogen (H−)
A fundamental negative ion used in accelerator injectors and sputter sources.
Deuterium (D−)
Used in fusion/neutron sources and ion source development.
Lithium (Li−)
A low‑Z negative ion often produced in cesiated sputter sources.
Carbon (C−)
A commonly produced negative ion from graphite sources.
Oxygen (O−)
A high‑current negative ion from oxide targets.
Sodium (Na−)
An alkali negative ion produced from Na/NaCl targets.
Medium Ions Z 15–40
Chlorine (Cl−)
A common halogen ion produced in chloride targets.
Argon (Ar)
A workhorse ion species used in many accelerator and ion source testbeds.
Copper (Cu−)
A metal negative ion used in materials and accelerator studies.
Bromine (Br−)
A halogen negative ion from halide salts.
Zirconium (Zr−)
A refractory metal negative ion used in heavy ion beams.
Heavy Ions Z > 40
Molybdenum (Mo−)
A refractory metal negative ion.
Silver (Ag−)
A metal negative ion for surface science and sputtering.
Iodine (I−)
A halogen negative ion from iodide salts.
Tantalum (Ta−)
A heavy refractory metal negative ion.
Tungsten (W−)
A high‑Z negative ion with low beam current.
Gold (Au−)
A heavy metal negative ion used for high‑Z studies.