BNL, Upton, New York, USA
WEXBA1
BNL, Upton, New York, USA
BNL, Upton, New York, USA
| Paper | Title | Page |
|---|---|---|
| TUPLM25 | Connecting Gas-Scattering Lifetime and Ion Instabilities | 430 |
|
||
| Recently there is a renewed interest in fast ion instability (FII) which is of concern for future low-emittance electron storage rings, such as MBA light sources and colliders, i.e. eRHIC. While analytical theories and numerical codes exist to model the effect, due to various assumptions and limitations, accurate experimental verification is often desirable. Unfortunately, one of the most critical parameters for FII (as well as the classical "trapped-ion" instability), the residual ion concentration, is usually the most uncertain. Vacuum gauges and residual gas analyzers (RGAs) provide some useful data, but they are often not accurate enough, and, more importantly, they cannot directly probe the ion concentration along the beam orbit. In this paper we show how one could use gas-scattering lifetime measurements to infer the residual gas concentration suitable for ion instability experiment modelling. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM25 | |
| About • | paper received ※ 21 September 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
WEXBA1 |
Beam Dynamics Measurements with New Generation BPMs | |
|
||
| Due to state-of-the-art NSLS-II beam position monitors, combined with advanced signal-processing techniques, we are now able to measure the difference between the betatron tunes of two (or more) bunches stored in the ring with the accuracy better than 10-6. For bunches of unequal charge this allows us to precisely determine the transverse kick factors. By applying local bumps, or, for in-vacuum undulators (IVUs), by varying the gap, we can also precisely measure the impedance of individual ring components. Since the tunes of unequally charged bunches are measured simultaneously, this reference method is virtually immune to machine drifts, as well as other systematic errors. For instance, in our IVU measurements vs. undulator gap, we can accurately determine current-dependent tuneshifts two orders of magnitude smaller than the tuneshift induced by the natural focusing of the undulator. Other examples of measurements performed with similar, or related, techniques include single-shot measurements of tune-shift with amplitude as well as non-invasive lattice characterization during user operations. | ||
|
|
Slides WEXBA1 [5.935 MB] | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| WEPLM05 | Continuous Monitoring of Spectral Features of Electron Beam Orbit Motion at NSLS-II | 673 |
|
||
| NSLS-II ring is equipped with state-of-the art beam position monitors (BPMs) which are indispensable in all aspects of machine studies and operations. Among other data, they can provide, on demand, up to 10 seconds of fast-acquisition (FA) data, sampled at ~10 kHz. Analysis of these data in time, frequency and spatial domains provides valuable insights into orbit stability, locations of residual noise sources, performance of feedback systems, etc. In addition, changes in FA signal spectral features are often the earliest indicators of potential equipment problems. This is why we recently implemented an Input / Output Controller (IOC) software that runs during regular user operation, and, once a minute, acquires 10 second buffers of FA data from 180 BPMs around the ring. These buffers are processed to determine the amplitudes and frequencies of the strongest spectral peaks as well as some other measures of fast beam orbit noise. Processed results can be monitored in real time and are also archived for offline analysis and troubleshooting. In this paper we discuss the implementation of this system and the insights we gained from it over about two years of operations. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM05 | |
| About • | paper received ※ 31 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |