Particle beam source apparatus, system and method

An ion source comprising:

• a chamber disposed about a longitudinal axis and containing a gas;
• a magnetic confinement system configured to produce a magnetic field in a confinement region within the chamber, wherein the confinement region is disposed about the axis and extends along the axis from a proximal end to a distal end, and wherein the magnetic field comprises:
• a first magnetic mirror located at the proximal end of the confinement region;
• a second magnetic mirror located at the distal end of the confinement region;
• a substantially uniform magnetic field disposed about and directed substantially parallel to the longitudinal axis, the substantially uniform magnetic field being located between the first and second magnetic mirrors;
• and
• an electron cyclotron resonance driver which produces a time varying electric field which drives the cyclotron motion of electrons located within the confinement region, said driven electrons interacting with the gas to form a confined plasma;
• wherein, during operation, the magnetic confinement system confines the plasma in the confinement region such that a portion of atoms in the plasma experience multiple ionizing interactions with the driven electrons to form multiply ionized ions having a selected final ionization state;
• and wherein at least one of the following features is present:
• (i) the ion source comprises an ion cyclotron driver, which directs radiation to the confinement region to preferentially drive the cyclotron motion of ions in the plasma having a selected driven ionization state to increase the motional energy of said ions in directions perpendicular to the longitudinal axis;
• (ii) at least one magnetic mirror comprises a magnetic field extending outside of the confinement region;
• the electron cyclotron driver is tuned to the electron cyclotron frequency corresponding to a portion of the magnetic field extending outside of the confinement region to drive the cyclotron motion of unconfined electrons in said portion of the field, wherein said unconfined electrons interact with the gas to form an unconfined plasma;
• and the ion source further comprises a sputter target located in the chamber and proximal to said portion of the magnetic field, and biased to attract ions from the unconfined plasma, in response to collisions with the attracted ions, the sputter source emits neutral particles which form at least a portion of the gas of atoms;
• (iii) the gas comprises He atoms, and the magnetic confinement system confines the plasma in the confinement region such that a portion of He atoms in the plasma experience two singly ionizing interactions with the driven electrons to form alpha particles or 3He++ ions;
• (iv) the magnetic confinement system is further configured to produce a radial confinement magnetic field which confines the radial motion of the plasma away from the longitudinal axis and the radial confinement magnetic field does not substantially extend into the substantially uniform magnetic field;
• (v) the electron cyclotron resonance driver produces a time varying electric field having a frequency substantially de-tuned to the electron cyclotron resonance frequency corresponding to the substantially uniform magnetic field.