Hollow Electron Beam Collimator

The hollow electron beam collimator (HEBC) is a new concept for controlled halo removal in high-intensity storage rings and colliders such as the Tevatron or the LHC. It is based on the interaction of the circulating beam with a 5-keV, magnetically confined, pulsed electron beam in a short section of the ring. It complements traditional collimation systems beyond their intensity limits. It also mitigates the effects of loss spikes due to collimator steps or to beam jitter.

A hollow electron gun was designed and tested at Fermilab for this purpose. It was installed in one of the Tevatron electron lenses in August 2010. The concept was tested experimentally in the Tevatron starting in October 2010 until the shutdown of the machine in September 2011.

Applicability of the concept to the SPS or LHC machines at CERN is being studied. A conceptual design report was published in May 2014.







Transverse beam layout in the Tevatron Beam layout in the Tevatron

The transverse kick is

\theta = \frac{2 \,I_r \,L \,(1\pm \beta_e \beta_p)}{r \,\beta_e \,\beta_p \,c^2 \,(B \
ho)_p} \left( \frac{1}{4\pi \epsilon_0} \
\end{displaymath} .

Modeling and simulations

The 15-mm (0.6-in) gun



Filament heating data

Peak current yield of the 0.6-in hollow gun vs. voltage and temperature

0.6-in hollow gun calculated profile 0.6-in hollow gun calculated profile 0.6-in hollow gun calculated profile

Evolution of the hollow profile with increasing current in low solenoidal field

Transverse dependence of the time structure of the electron beam pulse

The 25-mm (1-in) gun


SAM calculations of peak current [A] vs. voltage and magnetic field [L. Vorobiev, Jan 2012]

B [kG] \ V [kV] 1 3 5 7 10
0.5 0.222 2.183 3.306 5.8
1 0.222 2.324 3.628 6.334
2 0.222 1.134 2.322 3.765 6.327
3.2 0.221 1.133 2.318 3.758 6.318
5 0.221 2.323 6.307

Data files can be found in the AFS project space

Mechanical design


Pictures taken in the linac lab Sep 23, 2011:

Electron gun assembly table in the linac lab Overview of some of the parts for the 1-in electron gun
Detail of the 1-in cathode Detail of the 1-in gun heat shields

More full-size pictures in this file archive: HG_1in_linac_lab_20110923.

The 1-in hollow gun was installed in the test stand on Oct 20, 2011.

Heating data for 1-in hollow electron gun (Oct 2011 - Jan 2012), PNG plot
[data] [PDF]


Tevatron studies

Electronic logbook

  • Store 8171, 13 Oct 2010
  • Store 8210, 27 Oct 2010
  • Store 8349, 9 Dec 2010
  • Store 8365, 15 Dec 2010
  • Store 8415, 11 Jan 2011
  • Store 8430, 19 Jan 2011
  • Store 8466, 31 Jan 2011
  • Store 8467, 3 Feb 2011
  • Store 8508, 17 Feb 2011
  • Store 8527, 25 Feb 2011
  • Store 8546, 3 Mar 2011
  • Store 8709, 4 May 2011
  • Store 8733, 13 May 2011
  • Store 8749, 20 May 2011
  • Store 8763, 24 May 2011
  • Store 8764, antiproton-only, 24 May 2011 (All_Devices_pbar_only.xml)
  • Extinction scans, 150-GeV protons, 27 May 2011 (Extinction_scans.xml, Coll_pos_fast.xml)
  • Store 8816, 14 Jun 2011
  • Store 8820, 16 Jun 2011

The attached file (All_Devices.xml) is used to extract ACNET data using Batch Data Logger Extractor. For large data sets (several hours), the SBD array devices can be extracted separately (SBD_devices.xml). Also, fast loss monitors (logged at 15 Hz) have their own description file (Fast_Loss_Monitors.xml).

Compressed ACNET data files are available in the project's AFS space.

Data analysis tools

Data analysis carried out using the open-source, multi-platform statistical package R.




Removal rates

Effects on the core

Collimation efficiency

Mitigation of beam jitter

Pulsing patterns

Application to the LHC