PCaPAC 2000, Oct.9 ~ 12, 2000 Page 1

BLM System for NSRL HLS

PC and CAN Bus in Beam Loss Monitor System for NSRL

Yonggang Cui, Beibei ShaoDepartment of Engineering Physics, Tsinghua University

Yuxiong LiNational Synchrotron Radiation Laboratory

PCaPAC 2000, Oct.9 ~ 12, 2000 Page 2

BLM System for NSRL HLS

Introduction to NSRL HLS

Implementation of BLM System

Results and Analysis

Conclusions

Contents

Contents

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BLM System for NSRL HLS

Introduction to NSRL and HLS

First National Laboratory in China dedicated to Synchrotron Radiation

66.35m long, 800MeV electron storage ring – Hefei Light Source, with a 200MeV linac as its injector

New Beam Loss Monitor System (BLM System ) installed in Phase II project.

Introduction to NSRL and HLS

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BLM System for NSRL HLS

The System employs PIN-photodiodes BLM detector

designed by DESY. Detection efficiency to electrons (MIP) is 30%, 3 magnitudes

higher than that to gamma ray

Insensitive to gamma ray and background of synchrotron radiation

around the electron storage ring

The system gives beam losses information by detecting the

charged shower particles produced by beam loss electrons

when hitting the vacuum wall.

Principle of Detecting the Beam Losses

Introduction to NSRL and HLS

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BLM System for NSRL HLS

Scheme of BLM System Structure

Distributed system based on CAN bus.

PC with Windows 98/NT

is employed as console.

16 frontend machines distribute

along the storage ring. 12 frontend machines are

placed behind the bending magnets.

The others locate at interested points, e.g. the end of straight section.

Every front-end can drive two BLM detectors

CAN BUS

PC Console withWindows 98/NT

… ...Front-end

BLMDetectors

Implementation of BLM System

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BLM System for NSRL HLS

Console with 98/NT

… ...Front-end

BLMDetectors

Scheme of BLM System Structure

Independent System Structure Because the new control system

has not finished yet when the BLM system was designed.

Integration to the whole system is simple The communication part of

console software => Middle layer

The displaying part of console software => top layer

CAN BUS

WSorPC

Terminal

Ethernet

VME

or

PC

Implementation of BLM System

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BLM System for NSRL HLS

Frontend Machine and Pulse Accumulator Every front-end can be divided into 3 parts:

MCU Module

CAN Bus Module

Counter Module. The pulse accumulator in counting module:

Two channels

Counting frequency higher than 10MHz

Free running ability: working continuously without losing any pulses, even when accessed by MCU

EPLD Implemented (ALTERA)

CANBUS

Dual-ChannelPulse Accumulator

Pulses Input

SignalCondition

CANController

CANDriver

CANAddress

ROM( 8K )

RAM( 40K )

MC68HC11A1MCU

Clock

RS-232

Addr/Data BUS

MCU Module

CAN BUS Module

LED &Control

Counter Module

Implementation of BLM System

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BLM System for NSRL HLS

CAN Bus Communication in BLM System

CAN Bus High speed differential bus with high reliability and robustness Multi-master and broadcast bus cost-effective design

Solution CAN interface board on PC Cheap total solution from Philips for frontend Define the message format of data frames instead of using thee

standard CAN application layer, e.g CAL, CANopen The definition is implemented as Simple CAN Application

Interface (SCAI) in C language

Implementation of BLM System

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BLM System for NSRL HLS

Implementation of Software

CAN BUSDevice Driver

BeamEyesApplication Software

(Microsoft Visual C++ 6with MFC)

CAN BUS

CAN BUSISR & I/O Function

DAQ Software

PCConsole

Front-end

Document:CBeamEyesDoc

View 1:CCrossView

View 2:CCurveView

Display BLM data in histogram

Display BLM data in curves

• Collecting Option

• Beam Loss Data

• System ParametersPointers

SCAI

SCAI

Implementation of BLM System

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BLM System for NSRL HLS

Result I

Beam lifetime includes

Quantum lifetime Inelastic scattering Touschek lifetime

Beam lifetime, esp. quantum lifetime became much more worse due to operators’ changing the running parameters

Results and Analysis

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BLM System for NSRL HLS

Result II

Results and Analysis

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BLM System for NSRL HLS

Conclusions

The System is sensitive enough to detect beam losses. Right selection of BLM detector Correct design of pulse accumulator

The BLM system based on PC and CAN bus is fast enough for real-time display. CAN bus is a high speed, high reliability bus. It’s a right

candidate in field control. PC with Microsoft windows operating system is a reasonable

selection in slow speed system.

Conclusions

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BLM System for NSRL HLS

Conclusions (continue)

The BLM system can not only detect the beam losses, but also give much more help on machine study. Finding the reason of beam losses Optimizing the storage ring’s running parameters beam lifetime study

Conclusions

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BLM System for NSRL HLS

Picture of the Frontend Machine

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BLM System for NSRL HLS

The End