Measured gas desorption and electron cloud effects with an intense ion beam in a solenoid lattice

• Published in: Physical review special topics. PRST-AB. Accelerators and beams Vol. 11; no. 5; p. 050103
• Main Authors: Coleman, J. E., Seidl, P. A., Vay, J. L., Molvik, A. W., Sharp, W. M.
• Format: Journal Article
• Language: English
• Published: United States American Physical Society 01-05-2008
• ISSN: 1098-4402; 1098-4402
• DOI: 10.1103/PhysRevSTAB.11.050103

Electron cloud and gas measurements were conducted in a solenoid lattice with a 10  μs, singly charged K^{+} ion bunch at an ion energy of 0.3 MeV and currents of 26 and 45 mA. The principal objective of these experiments is to control electrons and understand their impact on the beam dynamics. Electron clearing measurements indicate an electron density close to 1% of the beam density in the solenoid lattice is enough to partially neutralize the beam and cause the emittance to grow ≥40%. A new method of measuring the dynamics of beam-induced gas desorption, ionization, and electron emission for normal incidence is also presented. Stainless steel and copper targets exposed to a beam intensity of 1.6×10^{12}  ions/pulse show ionized gas and electron densities approach the beam density in a single pulse. These measurements also show the gas cloud expands as a function of time and the dynamics are dependent upon the incident material and the bias voltage.