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Title: Fast Beam Loss Diagnostic to Quantify Charge Deposition in APS Superconducting Undulators

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Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
Argonne National Laboratory - Advanced Photon Source; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: ICFA Beam Dynamics Newsletter; Journal Volume: 66
Country of Publication:
United States
APS Superconducting Undulators; Fast Beam Loss Diagnostic

Citation Formats

Dooling, Jeffrey C., Harkay, Katherine C., and Ivanyushenkov, Yury. Fast Beam Loss Diagnostic to Quantify Charge Deposition in APS Superconducting Undulators. United States: N. p., 2015. Web.
Dooling, Jeffrey C., Harkay, Katherine C., & Ivanyushenkov, Yury. Fast Beam Loss Diagnostic to Quantify Charge Deposition in APS Superconducting Undulators. United States.
Dooling, Jeffrey C., Harkay, Katherine C., and Ivanyushenkov, Yury. 2015. "Fast Beam Loss Diagnostic to Quantify Charge Deposition in APS Superconducting Undulators". United States. doi:.
title = {Fast Beam Loss Diagnostic to Quantify Charge Deposition in APS Superconducting Undulators},
author = {Dooling, Jeffrey C. and Harkay, Katherine C. and Ivanyushenkov, Yury},
abstractNote = {},
doi = {},
journal = {ICFA Beam Dynamics Newsletter},
number = ,
volume = 66,
place = {United States},
year = 2015,
month = 4
  • We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 (“ID6”) since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 (“ID1”) in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenchingwhen the SCU0windings are nearmore » critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in ID6 on the SCU0 chamber transitions and in ID1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.« less
  • Fast fiber-optic (FFO) beam loss monitors (BLMs) installed with the first two superconducting undulators (SCUs) in the Advanced Photon Source storage ring have proven to be a useful diagnostic for measuring deposited charge (energy) during rapid beam loss events. The first set of FFOBLMs were installed outside the cryostat of the short SCU, a 0.33-m long device, above and below the beam centerline. The second set are mounted with the first 1.1-mlong SCU within the cryostat, on the outboard and inboard sides of the vacuum chamber. The next 1.1-m-long SCU is scheduled to replace the short SCU later in 2016more » and will be fitted with FFOBLMs in a manner similar to original 1.1-m device. The FFOBLMs were employed to set timing and voltage for the abort kicker (AK) system. The AK helps to prevent quenching of the SCUs during beam dumps [1] by directing the beam away from the SC magnet windings. The AK is triggered by the Machine Protection System (MPS). In cases when the AK fails to prevent quenching, the FFOBLMs show that losses often begin before detection by the MPS.« less
  • A thin foil Faraday cup array is being built to measure the loss of 3.5 MeV alpha particles and MeV ion cyclotron heating tail ions on Joint European Torus. It will consist of nine detectors spread over five different poloidal locations and three radial positions. They will measure the poloidal distribution and radial scrape off of the losses. The detectors will be comprised of four layers of thin (2.5 {mu}m) Ni foil, giving some resolution of the lost particle energy distribution as different ranges of energies will stop in different layers of the detector. One detector will utilize eight thinnermore » (1.0 {mu}m) foils to obtain a better-resolved energy distribution. These detectors will accept particles incident up to 45 deg. from the normal to the foils.« less
  • A new scintillator-based fast ion loss detector has been installed on DIII-D with the time response (>100 kHz) needed to study energetic ion losses induced by Alfven eigenmodes and other MHD instabilities. Based on the design used on ASDEX Upgrade, the diagnostic measures the pitch angle and gyroradius of ion losses based on the position of the ions striking the two-dimensional scintillator. For fast time response measurements, a beam splitter and fiberoptics couple a portion of the scintillator light to a photomultiplier. Reverse orbit following techniques trace the lost ions to their possible origin within the plasma. Initial DIII-D resultsmore » showing prompt losses and energetic ion loss due to MHD instabilities are discussed.« less
  • The prompt loss of neutral beam ions from the National Spherical Torus Experiment is expected to be between 12% and 42% of the total 5 MW of beam power. There may, in addition, be losses of fast ions arising from high harmonic fast wave (HHFW) heating. Most of the lost ions will strike the HHFW antenna or the neutral beam dump. To measure these losses in the 2000 experimental campaign, thermocouples in the antenna, several infrared camera views, and a Faraday cup lost ion probe will be employed. The probe will measure loss of fast ions with E>1 keV atmore » three radial locations, giving the scrape-off length of the fast ions.« less