Operating a cesium sputter source in a pulsed mode.

Area of Science:

• Atomic and Molecular Physics
• Accelerator Physics

Background:

• Cesium sputter negative ion sources are crucial for various applications.
• Continuous wave (DC) operation can lead to rapid cathode degradation, limiting experimental duration and material choices.
• Studying photodetachment processes requires precise control over ion beam delivery.

Purpose of the Study:

• To present a scheme for pulsing a cesium sputter negative ion source.
• To evaluate the benefits of pulsed ion beams for photodetachment studies.
• To assess the impact of pulsed operation on cathode lifetime and ion current.

Main Methods:

• Periodically switching the high voltage of the cesium sputter negative ion source on and off.
• Combining the pulsed ion beam with a pulsed laser (6 ns pulse length, 10 Hz repetition rate).
• Comparing cathode lifetime and peak ion current in pulsed mode versus DC operation.

Main Results:

• Pulsed mode operation increased cathode lifetime by two orders of magnitude compared to DC operation.
• Peak ion current in pulsed mode showed strong species-dependent variations, with some elements exhibiting significant enhancement.
• The effectiveness of pulsed mode for ion current enhancement varies by element.

Conclusions:

• Pulsed operation of cesium sputter negative ion sources offers substantial advantages in cathode longevity.
• This technique is particularly beneficial for experiments involving negative ions with short cathode lifetimes, expensive materials, or low intrinsic yields.
• Pulsed ion beams enable efficient photodetachment studies by maximizing the use of the ion source during experimental runs.