# Presentation: 143772

## Bunch Cleaning System

**Fernando Sannibale**
**W. Barry, W. Byrne, M. Chin, R. Duarte, H. Nishimura, J. Oneill**

## Contents

**ALS Topoff Upgrade**
**1****st**** Project Review**
**November 23, 2004**

** ****Motivation & Considerations**
** ****Proposed Bunch Cleaning System**
** ****Storage Ring Cleaning System Upgrade**
** ****Storage Ring Bunch Purity Monitor**

**Contents**

## Motivation& Considerations

**ALS Topoff Upgrade**
**1****st**** Project Review**
**November 23, 2004**

**Motivation& Considerations**

** ****Experiments with long relaxation time **
** ****Top journals publications**
** ****4 weeks/year “two bunches mode”. **
**     ****(Distance between bunches ~ 330 ns)**
** ****Actual cleaning system exploits tune shift with current**
** ****Non compatible with top-off**
** ****Proposed system: cleaning in the booster**

## Bunch Cleaning System Scheme

**ALS Topoff Upgrade**
**1****st**** Project Review**
**November 23, 2004**

**Light sources using or testing such a scheme:**
** ****APS**
** ****Spring 8**
** ****ESRF**
** ****Successful test at the ALS storage ring**

**Bunch Cleaning System Scheme**

- Betratron sideband
- frequency

- Bunch selector signal
- (synch. with RF)

- N. Sereno, Proceedings of the 1999 Particle Accelerator Conference, New York, US, 1999, p. 2322.
- H. Suzuki, *et al*., Nuclear Instruments and Methods in Physiscs Research A 444 (2000) 515-533.
- T. Aoki, *et al*., Proceedings of the 2003 Particle Accelerator Conference, Portland, US, May 2003, p. 2551.
- E. Plouviez, ESRF Machine Technical Note 01-04/MDT.

##  Bunch Cleaning System Basics

**ALS Topoff Upgrade**
**1****st**** Project Review**
**November 23, 2004**

** ****Bunch Cleaning System Basics**

**ALS stripline transverse kicker: **

| Electrode length (l) | 30 [cm] | Electrode diameter (d) | 70 [mm] |
| --- | --- | --- | --- |
| Electrode subtend angle () | 120 [deg] | Characteristic impedance (ZL) | 50 [] |

- H. Suzuki, *et al*., Nuclear Instruments and Methods in Physiscs Research A 444 (2000) 515-533.

## Booster Cleaning Systems

**ALS Topoff Upgrade**
**1****st**** Project Review**
**November 23, 2004**

**Booster Cleaning Systems**

**SR Transverse feedback amplifiers match the requirements**

| Beam energy at cleaning | 300 MeV | Natural vertical chromaticity | - 4.61 |
| --- | --- | --- | --- |
| Booster revolution period   (T0) | 250.2 ns | Operation vertical chromaticity | 0.0 ± 0.1 |
| RF frequency | 500 MHz | Vertical Tune | 2.72 |
| Harmonic number | 125 | Vert. excitation frequency | ~ 1.12 MHz |
| Long. Damp. time @ 300 MeV | ~ 400 ms | Max tune variation at  E/E = 0.5%    (y | ~ 5 × 10-4 |
| Transv. damp. time @ 300 MeV (d) | ~ 800 ms | Vertical kick angle ( | ~ 6.3 rad |
| Vertical beta function at scraper position  (Sc) | ~ 10 m | Kicker type | stripline |
| Vertical beta function at the kicker position  (K) | ~ 10 m | Kicker shunt impedance | ~ 9000   |
| Distance vertical scraper-reference orbit  (y) | 10 mm | Amplifier power (P) | ~ 200 W |
| Energy spread at 300 MeV (rms)
(1% rms linac energy spread @ 50 MeV) | ~1.7×10-3 | Amplifier bandwidth | > 200 MHz |

**Cleaning in the Booster during energy ramping**
** ****1 ms cleaning is sufficient, ~ 10 ms is safer**

## Booster Cleaning System

**ALS Topoff Upgrade**
**1****st**** Project Review**
**November 23, 2004**

**Booster Cleaning System**

**Vertical kicking allows leaving**
**scraper in during Booster injection**

**Kicker and scraper can**
**be in different periods**

## Storage RingCleaning System Upgrade

**ALS Topoff Upgrade**
**1****st**** Project Review**
**November 23, 2004**

**Storage Ring****Cleaning System Upgrade**

** ****In some conditions, a high purity injection alone could not be sufficient. **
** ****If the dynamic aperture of the storage ring is larger than the RF bucket size, diffusion from the main bunches to the near ones can happen. **
** ****In such a case, a periodic cleaning in the storage ring will be required as well.**
** ****We propose to include in the storage ring a cleaning system similar to the one in the Booster.**
** ****The more expensive system components are already present in existing subsystems in the ring. **
** ****The system will use the existing transverse feedback system amplifiers and kickers jointly with the existing vertical scraper.**
**An additional arbitrary function generator is required**** **

## Storage RingBunch Purity Monitor

**ALS Topoff Upgrade**
**1****st**** Project Review**
**November 23, 2004**

**Storage Ring****Bunch Purity Monitor**

** ****Visible and x-ray Options:**
** ****Visible: gated MCP PMT, max resolution ~ 10****-4**
** ****Easier to implement - cheaper**
** ****X-rays: APD, max resolution ~ 10****-7**
** ****New port is required - more expensive**