Space-charge effects in ionization beam profile monitors

Studies of Beam Intensity Effects in Fermilab Booster Synchrotron

“…To be certain that we properly account that and other, intensity-independent, effects, we -in addition to following the theoretical recipes of Ref. [45] as described in Sec.IV A -has performed a systematic calibration of the IPM with the MultiWires measurements. As the result, we have achieved O(10)% accuracy in the beam emittance reconstruction using the measured IPM rms beam sizes, experimentally determined intensity-independent instrumental dispersion σ T , known beam intensity N p and the IPM parameters such as extracting electric field E ext = V 0 /D and the distance d from the beam orbit to the IPM detector.…”

“…9. Comprehensive theory of the IPM operation is developed in [45]. The rms size of the measured profile in the IPM σ m is related to the original proton beam size σ 0 as:…”

“…Here V is the IPM extracting voltage (typically, 24 kV in our case) and D is its HV gap (103 mm), d is the distance for ions to travel from the beam orbit to the IPM collection plate, the space-charge potential for the proton beam with current I is U SC = 30[V]I/β p and gamma function Γ(1/4)≈3.625. The numerical factor F is equal to 1 in the case of unbunched DC proton beam with Gaussian transverse current distribution, and Also very important are intensity independent effects leading to the IPM profile smearing such as the initial velocities of the ions, finite separation between the individual IPM charge collection strips, angular misalignment of the IPM long and narrow strips with respect to the high energy proton beam orbit, etc [45]. These effects are monitor-specific, they add in quadrature and can be determined in comparison of low intensity beam sizes measured by the IPM and by the MWs…”

Beam physics research with the IOTA electron lens

“…According to an analysis presented in ref. [116], the expansion of the ions due to the charge of the proton beams is minimal (of the order of 1%, compared to factors as large as 2 in the Booster), introducing negligible systematics in the turn-by-turn reconstruction of the proton beam profiles.…”

A gas curtain beam profile monitor using beam induced fluorescence for high intensity charged particle beams

“…Both residual gas and gas curtain IPMs would suffer from distortions due to space charge 25 and external electromagnetic fields in the LHC and HEL, where 1 T magnetic field is estimated at the diagnostic location. This leaves BIF monitors using a gas curtain with a short-lived ionic or a neutral emitter as the most feasible solution to measuring a two-dimensional transverse beam profile in machines, where the beams have high intensity and destructive power.…”