IOTA electron lens


The electron lens for the Integrable Optics Test Accelerator (IOTA) at the Fermilab Accelerator Science and Technology facility (FAST) has several purposes:

  • to act as nonlinear element for integrable optics
    - axially symmetric lens in solenoid
    - McMillan lens
  • to provide electron cooling for protons
    - to improve lifetime and enable experiments on space-charge dynamics
    - to study the interplay between cooling and nonlinear integrable optics
  • to enable experiments on space-charge compensation in rings with trapped electron columns

The design of the device is ongoing and it is scheduled to be completed in 2019. Construction and installation of the device is planned for 2020-2021.


  • Alexey Burov: electron cooling
  • Kermit Carlson: electrical engineering
  • Brandon Cathey: electron gun design and testing
  • Darren Crawford: operation, diagnostics
  • Ram Dhuley: solenoid cryocooler design and engineering
  • Nathan Eddy: instrumentation
  • Ben Freemire: electron-column simulations, diagnostics
  • Antti Kolehmainen (CERN): design and engineering
  • Valeri Lebedev: electron cooling
  • Sergei Nagaitsev: electron cooling, nonlinear integrable optics
  • Lucy Nobrega: mechanical engineering and vacuum
  • Chong Shik Park (Korea U. Sejong): electron-column simulations
  • Diego Perini (CERN): design and engineering
  • Ari Pikkarainen (Kemi U. Finland): design and engineering
  • Aleksandr Romanov: lattice design
  • Jinhao Ruan: operation
  • Vladimir Shiltsev: concept, physics, electron column
  • Giulio Stancari: design, physics, operation, team leader
  • Charles Thangaraj: concept of cryocooler for main solenoid
  • Linda Valerio: mechanical engineering and vacuum
  • Alexander Valishev: design, physics

Beam Dynamics

Templates for Lifetrac simulations of McMillan case with variable electron-lens strength [ZIP archive]


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IOTA Electron-lens section

Layout of the electron lens in the IOTA ring (as of Oct. 17, 2019):

IOTA_ELENS_17OCT19_iso.png IOTA_ELENS_17OCT19_iso_cut.png
Isometric view Isometric view, mid-plane cut
IOTA_ELENS_17OCT19_top_cut.png IOTA_ELENS_17OCT19_side_cut.png
Top view, cut Side view, cut

3D model of the IOTA e-lens section in STP format: Compressed archive

Baseline model of the magnetic system by Giorgia Gobbi (CERN), July 2019 [COMSOL file]

2D views of the e-lens section:

Electron_Lens_Section.png F10082015-1_elens_side_view.png F10082015-2_elens_top_view.png
E-lens section [PDF] Side view [PDF] Top view [PDF]

Magnetic system

The magnetic system consists of

  • Electron-gun solenoid (existing, from TEL-2)
  • Transport solenoid
  • First toroidal section
  • Main solenoid
  • Second toroidal section
  • Second transport solenoid
  • Collector solenoid (existing, from TEL-2)
  • Orbit correctors for the circulating beam to compensate for the toroid kick

The layout of the system was optimized in this report, taking into account the dynamics of the magnetized electron beam with space charge.

Layout of the magnetic system [PDF]

Gun and collector solenoids

Gun and collector solenoids were reused from one of the Tevatron electron lenses (TEL-2).

Electrical and water flow measurements in Fermilab Technical Division, 9 Nov 2016:

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Beam Current

Cathode and collector toroids

Beam Position Monitors (BPMs)

Two stripline BPMs in the overlap region

Profile measurements

YAG screen and pinhole after the second toroidal section


Split electrodes

For confinement and ion removal in the overlap region

electrode_layout.png F10092939_electrodes.png

Recombination monitor

Based on downstream detection of neutral hydrogen (for protons only, in electron-cooling mode) for cooling optimization and proton profiles

Microwave antenna

To detect synchrotron radiation from cyclotron motion for measuring the solenoid field and for estimating electron density and electron temperature

Calculation of expected signal power: C. Rubbia, Microwave radiation from the transverse temperature of an intense electron beam confined by a longitudinal magnetic field, CERN-EP-INT-77-4





Electronic logbooks

Related projects