An Automatic Control System of the Synchrotron ... - Springer Link

ISSN 00204412, Instruments and Experimental Techniques, 2011, Vol. 54, No. 3, pp. 323–334. © Pleiades Publishing, Ltd., 2011. Original Russian Text © V.G. Karaichentsev, S.I. Zheludeva, M.V. Kovalchuk, M.G. Kuznetsov, A.A. Mozgin, A.Yu. Seregin, E.Yu. Tereshchenko, V. F. Chistyunin, S.N. Yakunin, 2011, published in Pribory i Tekhnika Eksperimenta, 2011, No. 3, pp. 33–45.

APPLICATION OF COMPUTERS IN EXPERIMENTS

An Automatic Control System of the Synchrotron Station and Special Features of the Experiment Automation at the LANGMUIR Station of the Synchrotron Radiation Source of the RRC Kurchatov Institute V. G. Karaichentseva, S. I. Zheludevaa†, M. V. Kovalchukb,c, M. G. Kuznetsova, A. A. Mozgina, A. Yu. Sereginb, E. Yu. Tereshchenkob, V. F. Chistyunina, and S. N. Yakuninc a OOO NPTs “SYSTAL”, Tretii Zapadnyi pr. 17, str. 4, Zelenograd, Moscow oblast, 124460 Russia Institute of Crystallography, Russian Academy of Sciences, Leninskii pr. 59, Moscow, 119333 Russia c Kurchatov Center of Synchrotron Radiation and Nanotechnologies, Russian Research Centre Kurchatov Institute, pl. Akademika Kurchatova 1, Moscow, 123182 Russia

b

Received November 1, 2010

Abstract—A universal software–hardware architecture of the automatic control system (ACS) of the Xray experiment for synchrotron stations is designed. The designed ACS ensures the reliable longtime control of the station equipment from remote terminals located in safety zones. A hierarchical threelevel architecture of the control system based on personal industrial computers and specialized microcontrollers is selected to realize the hardware part. Data channels are based on Ethernet, RS485, and RS232 interfaces. The ACS software embodies the functional–modular principle and contains monitor modules with parametric adjust ment, group control modules of functional station blocks, and modules for individual control of mechanisms. Data exchange between the modules is supported by TCP/IP, DCON, and other standard communication protocols. When the control system was being designed, the possibility of expanding the system by embedding bought articles from leading manufacturers was without fail taken into account. The designed system allows its integration with automated experiment control systems. The work presents details of the designed ACS realization on the LANGMUIR multipurpose research technological system of the synchrotron radiation source of the Russian Research Centre (RRC) Kurchatov Institute, the Russian synchrotron station intended for studying interfaces of various nature by using a wide spectrum of precision surfacesensitive and spectrum selective Xray technologies, in particular, for studying organic and bioorganic nanosystems on liquid sur faces and various planar nanostructures on solid substrates. The specific character of the LANGMUIR sta tion invited development of a unique software–hardware module for controlling optical elements deflecting the beam from the horizontal line (beam control module), and creation of a special software unit for integrat ing the fluorescence signal recording section into the ACS and synchronization of the Xray and fluorescence sections. DOI: 10.1134/S0020441211020254 †

INTRODUCTION

The intense development of nanotechnologies, which has been lately observed all over the world, called for creation and development of adequate methods of nanodiagnostics, due to which it will be possible to obtain information on structures and com positions of nanoobjects and systems on their basis. The existing and currently designed nanoobjects are extremely diverse. In particular, they include various semiconductor and metallic multilayer and surface structures (used, e.g., as a base of solidstate nanoelec tronics, i.e., superlattices, heterostructures); organic and bioorganic laminar nanostructures (which are the base of molecular organic nanoelectronics and are used for creating various gaseous, chemo, and bio † Deceased.

sensors and for designing models of cellular biomem branes, i.e., molecular architecture), etc. When these systems are designed, the need arises for studying the surface, nearsurface layers, and inner interfaces, in particular, the surface structure, interdiffusion of ele ments, and selforganization processes. Investigations of proteinlipid films on the liquid subphase surface, in which the native conformation of protein molecules is not violated and, hence, their biological functions are preserved, gain a special urgency for fundamental and applied studies in biol ogy and medicine. This provides a means in principle to simulate various biophysical and biochemical pro cesses in biologically active functioning membranes. Moreover, additional advantages of investigations of proteinlipid layers on the liquid subphase are attribut

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Детектор

Монитор

Помощь

29.11.2007 16.15.47

О программе

Выход

Д1

Панель контроля состояния устройств Датчик пучка Фильтры 1 Фильтры 2 ЭКСПЕРИМЕНТ ИЗМЕРЕНИЯ

Параметры УСТРОЙСТВА Входные щели Монохроматор 1 Выходные щели Управления пучком 2 Выходные щели Регистрация и Образец Синхронизация вкл. выкл. сброс пучка

ТОК 0

Старт

Контроль канала управления

Сибирь 2 Старт

Графика Москва 2006 версия 1.1.44

Fig. 1. Xray optic scheme of the LANGMUIR station.

able to a possibility of simulating various functioning conditions of biomembranes in bioplasts. It is possible to use various surfacesensitive Xray methods to obtain structural data on laminar nanosys tems (reflectometry, smallangle scattering, two dimensional surface diffraction, etc.). At the same time, for diagnostics of multicomponent nanostruc tures, it is expedient to attract methods capable of pro viding spectralselective information. It is possible to perform these studies only at spe cialized experimental stations by using a highintense synchrotron radiation (SR). The originality of the LANGMUIR synchrotron station is that the designed structure provides a means for studying various planar laminar nanostructures (inorganic, organic, and bioorganic) both on a liquid surface and on solid sub strates by using a wide spectrum of surfacesensitive and spectralselective Xray technologies (Xray fluo rescent analysis, Xray standing waves method at the total reflection condition, reflectometry, smallangle scattering, and twodimensional surface diffraction). There are several stations in the world, on which it is possible to study organic layers on the liquid surface.

In Russia, the LANGMUIR research–technologic system of the synchrotron radiation source at the RRC Kurchatov Institute is the first Russian synchrotron station intended for performing these unique studies [1, 2]. The synchrotron radiation beam control method was designed and used at the station. This method pro vides for tilting of the radiation beam to the horizontal surface, allowing one to preserve immobility of the Langmuir bath during the experiment. The LANGMUIR station contains several func tional modules (Fig. 1): (i) beam extraction and trans portation system, (ii) monochromatization block, (iii) slit blocks, (iv) beam control block, (v) filter blocks, (vi) sample block, and (vii) recording block. The station includes precision electromechanical units, sensors, and control research equipment. The SYSTAL–LANGMUIR automatic control system was designed for the prompt remote control of separate components of the station in the adjustment mode and for the complex control of functional mod ules of the station in the experiment control mode.

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AN AUTOMATIC CONTROL SYSTEM OF THE SYNCHROTRON STATION

TECHNICAL CHARACTERISTICS OF THE SYSTAL–LANGMUIR ACS The universal ACS has a twolevel architecture. The hardware part of the control system is based on commercially produced cards (controllers) of a per sonal computer with the Windows XP operational sys tem. The controllers made by leading world computer equipment manufacturers meet ISO 9001 interna tional industrial standard requirements. The hierar chical threelevel control system architecture based on personal and industrial computers and specialized microcontrollers [3] was selected to realize the hard ware part. The ACS software is modular and made as a multiwindow Windows XP application; it uses the client–server technology. The integration into the control system has been fulfilled for some station com ponents bought from outside manufacturers (for example, an Eyesys ConvecTorr vacuumlevel con troller from the Varian Co.). For experimentalist’s convenience, an interface with control forms of actu ating mechanisms, recoding units, and measurement performing and stationadjustment programs has been designed. To efficiently perform the station adjustment and experiments, a parameter table has been designed as a part of the computer control system program (all actu ating mechanisms are formalized in it). This allows one to perform flexible adjustment of linear and angu lar axes of the station during alignments of the actuat ing mechanisms. The main technical characteristics of the SYSTAL– LANGMUIR ACS are summarized in the table. In addition to the stated characteristics, the ACS con tains units of the outside manufacturers: (i) Eyesys ConvecTorr vacuumlevel controller from the Varian Co., and (ii) spectrometric equipment from the Canberra Co.

Table Parameter name Number of controlled electric drives


ACS 37

of them: – step motor drives – servo positioning piezodrives Number of controlled motion coordinates

36 1 36

of them simultaneously: – at the linear interpolation

5

– at the circular interpolation

5

Number of discrete signals

32

of them: – number of discrete inputs

16

– number of discrete outputs

16

Number of analog input signals

8

Number of served sensors: – of the temperature

5

– of the beam

2

– of the ionization chambers

3

– reference sensors (emergency movement limiters)

70

– of the vacuum

2

– of the BSXD (scintillation Xray detector)

1

Parameters of the primary power line Power consumption from the power line, W

ACS BLOCK DIAGRAM At the LANGMUIR station, the SYSTAL– LANGMUIR ACS hardware part is distributed throughout three control levels: (i) upper level, (ii) first lower level, and (iii) second lower level. The upper level is located outside the station and hardwarily con sists of the computer block with the remote control system and a computer providing the ACS with infor mation on the current in the ring of the synchrotron (SR) from the database of the informational system of the synchrotron radiation source at the RRC Kur chatov Institute. The lower levels of the control system are hardwarily placed in the protective house (“hatch”) of the station. The block diagram of the ACS is shown in Fig. 2. The lowlevel control system located inside the hatch ensures total control of the station and deter mines the reliability and accuracy of its operation. The computer block contains a fullsize calculator

325

Ambient temperature, °С Protection degree

220 V, 50 Hz 1500 +5 … +45 IP00

Mass, kg – Computer block

14

– Control unit 1

18

– Control unit 2a

12

(an industrialversion personal computer communi cating via RS485 channels with SYSTAL PIC9SM intelligent controllers for controlling displacements along the coordinate axes). Each intelligent controller has its own microprocessor, which maintains step motors and temperature sensors. The control system includes 37 intelligent controllers. Vol. 54

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KARAICHENTSEV et al. UpperFlevel control system

SibirF2

ULC

External hall

Ethernet

Informational network of the SR ring

USB

Mechanisms and and units of the LANGMUIR station

LowerFlevel control system

RSF232

RSF485

Compute block

Canberra detector

RSF232

Varian vacuum gage no. 1 Varian vacuum gage no. 2

Ethernet

RSF232 RSF232

Temperature sensors BSXD detector

Control unit no. 2

Ionization chambers

RSF485

Beammonitors Solid sample block

Hatch

Mechanisms and units of the monochromator

RSF485

Exit slit

RSF485

Sample and recording block

Control unit no. 1

Entrance slit Middle slit Filter block no. 1 Filter block no. 2 Beam control unit

Fig. 2. Block diagram of the SYSTAL–LANGMUIR ACS.

Almost a half of the step motor drives and the piezodrive operate in deepvacuum conditions. The electronics of the control system operates at an increased ozone concentration in the air. Therefore, the control system is made of industrial modules and units, i.e., those, which are protected against unfavor able environment conditions. The upperlevel computer (ULC) does not directly control the station. It is used to display information and set operation modes of the control system and does not contain station control modules. The selected experiment control program is loaded from

the ULC into the computer block of the lowerlevel control system and is executed by the computer block independently of the ULC. The operation conditions of the ULC are laboratory conditions. Therefore, a typical personal computer is used as a ULC. As a result, we have the threelevel control system. The personal computer is at the upper level. At the first lower level, there are fullsize industrial computers with a set of peripheral modules required for control ling the station. The second lower level contains intel ligent controllers controlling the step motors and the


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Information network of the SR ring Ethernet

USB

ULC

SibirF2

Ethernet

RSF232

Computer block

Calculator NuPROF760 Backbone CPF114

PCLF711

RSF485

Control unit no. 2

CIF134

RSF485

RSF485

PICF Thermo

“PD1, 3FIC”

Piezo motor no. 1

Ionization chambers

Temperature sensors

Beam monitors

Sensor no. 1

BSXD detector

Solid sample block

Varian vacuum gauge no. 2

Varian vacuum gauge no. 1

RSF485

Control unit no. 1 PICF9SM no. 1 TSM no. 2 TSM no. 1

Mechanisms and units of the LANGMUIR station

TSM no. 12

PICF RD2

PGU

Mechanisms and units of the LANGMUIR station

TSM no. 11

IF7024

PICF9SM no. 2 TSM no. 4

TSM no. 3

Mechanisms and units of the monochomator

PICF9SM no. 3

PICF9SM no. 4

TSM no. 8

TSM no. 10

TSM no. 6 TSM no. 5

TSM no. 7

TSM no. 9

Beam control unit

Filter lock no. 2

Sample and recording block

Entrance slit

Filter lock no. 1

Middle slit

Caberra detector

Exit slit slit

Fig. 3. Structural diagram and composition of the SYSTAL– LANGMUIR ACS.


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temperature sensors, as well as the power and match ing units. STRUCTURAL DIAGRAM AND COMPOSITION OF THE ACS The control system includes a set of subsystems interrelated by the common control, each fulfilling a specified complete part of the general problem [3]. The online multitask operation mode of the ACS com puters allows one to simultaneously control and moni tor all mechanisms and units of the LANGMUIR station. The structural diagram of the SYSTAL– LANGMUIR ACS is shown in Fig. 3. The computer block consists of the NuPRO760 fullsize calculator, PCL711 controller, CI134 con troller, and CP114 controller, which are all placed on the system backbone of the calculator. The PCL711 controller is the multifunction unit containing 8 ADCs, 1 DAC, 16 discrete TTL inputs, and 16 discrete TTL outputs. The PCL711 controller receives and processes analog data from the ionization chambers, controls operation of the piezodrive of the monochro mator, and controls (via discrete data input/output ports) operation of electromagnets of the beam moni tors by using powergenerating unit (PGU). The “PD1, 3FIC” unit is a highvoltage power supply for the ionization chambers and the piezodrive. The PIC Thermo unit receives and processes analog data from the temperatures sensors and is connected via the RS 485 channel to the CP114 controller. The CI134 controller is a communication adapter for four chan nels of the RS485 interface. All intelligent controllers are controlled via RS485 channels. The CP114 con troller contains two channels of the RS485 interface and two channels of the RS232 interface. Communi cation with the vacuum gauges is effected via the RS 232 channels and with temperature sensors via the RS 485 channel. The computer block is connected with the information network of the SR ring via one of the RS232 channels by the Sibir2 computer. Control unit 1 includes four PIC9SM and ten TSMF3 units. The PIC9SM unit is a ninechannel intelligent controller having nine microprocessors and controlling nine step motor drives. The TSMF3 is the power control converter of the step motor for three channels. Control unit 1 controls 30 coordinates of the LANGMUIR station and is connected to the com puter block via three RS485 channels. Control unit 2 includes the PICThermo unit, “PD1, 3FIC” unit, PGU unit, I7024 unit, PICRD2 unit, and two TSMF3 units. The PICThermo unit is a fivechannel intelligent controller servicing five temperature sen sors. The PGU unit controls operation of the electro magnets of the beam monitors by means of power units being parts of it. The “PD1, 3FIC” unit converts a low voltage received from the PCL711 controller into a high voltage for powering the piezomotor and generates highvoltage power for the ionization cham

bers. The I7024 unit is an intelligent controller con taining four DAC channels, which controls the PICRD2 unit. The PICRD2 unit is intended for processing signals from the Xray detector and acts as an amplitude analyzer. SPECIAL FEATURES OF THE SOFTWARE OF THE SYSTAL–LANGMUIR ACS The software is fulfilled on the functional–modular principle and contains: (i) monitor modules with parametric adjustment; (ii) group control modules for functional blocks of the station; and (iii) individual mechanism control modules. The data exchange between the modules is sup ported by TCP/IP, DCON, and other standard com munication protocols. The software operates on the Windows XP profes sional SP2 operational system platform. The interface is the multiwindow interface and operates in the fol lowing modes: (i) adjustment (alignment) of station components, and (ii) carrying out of experiments. The software of the control system contains four program modules: (i) main module; (ii) servo system module of the monochromator piezodrive; (iii) temperature control module in the cooling sys tem of the monochromator and beam control block; and (iv) vacuumlevel monitoring module. The main program module of the SYSTAL– LANGMUIR ACS performs control and monitoring of all mechanisms and sensors of the station, except for the control module of the servo piezodrive of the second crystal. The servo piezodrive module is made as a client application, and the data exchange is car ried out via the IP port according to the TCP/IP pro tocol. The vacuum and temperature levels are moni tored in the client–server mode. The server program (module) resides in the station control unit, and the client part resides in the upperlevel computer. The communication is effected according to the RS485 protocols for the temperature control channel and the RS232 protocols for the vacuum control channel. By means of software, the ACS supports monitor ing of 10 differenttype control channels: (i) 1st RS232 channel used to monitor the current in the synchrotron ring; (ii) 2nd RS232 channel used to control the servo piezodrive; (iii) 3rd–5th RS485 channels used to control the controllers of SYSTAL PIC9SM step motor drives; (iv) 6th RS485 channel used to control the con troller of the BSXD “SYSTAL PICFRD2”type detec tor and I7024 ICP CON DAC;


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Входные щели Координата Отн. Абс. 1ШВ

1ШН

1ШЛ

1ШП

Закрыть

Базирование

Движение Остановить

В базу

Продолжить

1ШВ 1ШВ = 0.00000

1ШП

Сброс

ШТОРКИ

0.00000 0.00000

0.00000

1ШЛ

0.00000 1ШН Координата – Размер щели Гориз.

0.00000

0.00000

Верт.

0.00000

0.00000

Коорд.Центра

Ширина

ВЫБОР ШТОРКИ Рабочая система координат

ЩЕЛЬ

Настройка

Fig. 4. Shutter setup and control form of the slit block.

(v) 7th channel of the PCL711B card, which is a servo system of the piezodrive and monitors the ion ization chambers and digital input/outputs for syn chronization with peripheral equipment; (vi) 8th RS485 channel used to control the SYSTAL PICThermo temperature controller; and (vii) 9th and 10th RS232 channels, which are the Eyesys ConvecTorr Varian vacuumlevel controllers. The channels are interrogated according to a pro tocol with a 10ms time step. There is its own timing diagram of interrogation for the correct operation of each channel. The interface gives the user an opportu nity of monitoring transmission of data and com mands in all channels. For the flexible adjustment of the optical system of the LANGMUIR station, the parameterization of the majority of main and auxiliary actuating mechanisms and monitoring units is used. This allows an experi mentalist to synchronize each axis with each required coordinate system and determine the motion direc tion, as well as the coordinates of control points and limiters. The ACS has two types of limiters: (i) physical (electronic) and (ii) mathematical. Parameters of all monitored blocks are saved and they can be saved for various experimental configurations under different names. In addition, the parameterization allows one to formalize some operations, e.g., to introduce com plex (compound, complicated) coordinate axes or use control channels by connecting other devices with INSTRUMENTS AND EXPERIMENTAL TECHNIQUES

identical drives. As part of the parameterization, each coordinate axis can have only one of two units of mea surement—millimeter or angular second. These val ues are saved in the adjustment table, which can be determined for various configurations of the experi ment adjustment. All current values of coordinates of axes are also saved in this table. By the experimental ist’s request, other units of measurement are pro grammed for complex coordinates. The main program contains its own interface for each station block, and this interface is represented as a separate window. For illustration, Fig. 4 shows a form for adjustment and control of shutters of the slit block. There are three slit blocks at the LANGMUIR station (see Fig. 1). They have identical design, and, therefore, the control forms are identical. Similarly, there are forms for control and adjustments of the monochromator, an ionization chamber, a mirror block, etc. The slit block is controlled in two modes, one of which implies independent motion of individ ual shutters, and the other—the slit motion mode— implies pairwise motion of vertical and horizontal shutters. In the second mode, complex coordinate axes—the coordinate of the center of the slit (vertical and horizontal) and the slit width—are introduced. By program, the ACS simultaneously executes the pairwise motion of these coordinates in the absolute and relative coordinate systems. The positioning accu racy is determined by converting the number of steps Vol. 54

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Монохроматор Координата Отн. Абс.

В базу

M1ω

M1ϕ

M1I

M1L

M2ω

M2ϕ

M2I

M2L

M2χ

M2ωT

M1ω =

[сек]

0.000

Движение


Остановить

Сброс

Длина волны λ

M2L

Базир.

Текущие координаты

M1ϕ

M1I

Закрыть

M2I M2ϕ

M2ω M1ω M2ωT M1L

M2χ Рабочая система координат Настройка

ГРАДУСЫ

СЕКУНДЫ

M2ωT

1.54

M1ω

1100.000

M2ω

44424.50

0.000

1.54

M1ϕ

0.00

M2ϕ

0.27

0.00000

M1I

0.00000

M2I

10.00000

M1L

30.00000

M2L

108.80600

M2χ

5.00000

Параметры

Установить

Следящая система

Fig. 5. Setup and control form of the monochromator block.

per the gear ratio of the actuating mechanism, which is introduced as a parameter. The motion error depends on mechanics. The most complicated control objects of the LANGMUIR station are the monochromator and beam control block. The monochromator contains nine step motors (SMs) and a servo piezodrive (see Fig. 5). Two complex coordinate λ and ω are intro duced to control the monochromator, and they are related to each other as a function of three coordinates М1ω, М2ω, and М2L. When the monochromator is tuned to the specified wavelength, positions of these three coordinates are calculated, and command for the simultaneous motion of the SM drives of these axes is produced. The control system ensures position ing control at a level of intelligent microcontrollers. At the end of motion, each motor is independently switched off from the control channel. To keep the required Xray beam intensity on the object of investi gation, fine tuning of angular coordinate М2ω is used during measurements with a 0.02″ accuracy. This accuracy is ensured by the servo piezodrive operating under control of the controller based on a PCL711B card. Figure 6 shows the form of the beam control block. The form implements the beam control algorithm [1, 2], which specifies displacement of the four coordinates constituting complex coordinate α (angle of incidence of the beam on the surface of the sample in the bath), as a function of axes Bγ1, Bγ2, B2L, and B2Z.

Radiation monitoring and adjustment of the Xray channel as part of the optical scheme is ensured by the beam sensors, ionization chamber, scintillation detec tor, and filters. The intensity data are digitized with ~3mV accuracy by a 5range 3channel recording unit based on a PCL711B card. For the experimen talist’s convenience, the program module of Xray beam intensity control, which has digital and graphic indication, is built into the software at the LANG MUIR station. For convenience of performing experiments, the control system includes the program taskforming module for any coordinate axis, including complex ones. There is a jobeditor for executing the task batch, and all jobs are based on patterns, which are saved into tasks and job lists under their own names. There are the following task patterns in the present version: (i) onedimensional; (ii) twodimensional; (iii) theta 2 theta; and (iv) detector. Each pattern contains an option for selecting an auxiliary recording unit, from measurement results of which the position of the maximum is determined. The station contains two ionization chambers and the detector for monitoring the Xray beam during align ment of the optical system. The results of radiation intensity measurements using the ionization chamber are saved (with reference to the axis) into files, which are introduced into the task patterns.


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AN AUTOMATIC CONTROL SYSTEM OF THE SYNCHROTRON STATION Блок управления пучком Координата Отн. Абс. Б1ϕ

Б1γ

Б2z

Б2L

Б1ϕ =

Б1z

БУПFконтроль Закрыть

Базир.

В базу

2Бz 2Бϕ 2БL

1Бϕ

0.000

[сек]

1Бγ Движение


Остановить

Сброс

Рабочая система координат

Параметры настройки

1Бz 2Бγ

Закрыть

α 1

[град]

Б1γ 0.15

[град]

Lo 900

[мм]

Ld 550

[мм]

ΔL 440

[мм]

Б2γ

Б2ϕ

331

Вычислить

Настройка

Открыть Сохранить

Текущие координаты

ГРАДУСЫ

СЕКУНДЫ

Сохранить как

Расчетные значения

Б1ϕ 10.000

Б2ϕ 0.00

Д2z 9.60029

[мм]

Б1γ 1007.34

Б2γ –577.02

Б2γ –0.64899

[град]

Б1z 0.00000

Б2z 0.29450

Б2L 692.30769

[мм]

Б2L 56.25000

Б2z 3.62491

[мм]

α 1

[град]

Параметры

Установить

СТОП

Б2Lmin 290.00000

[мм]

Б2Lmax 730.00000

[мм]

Fig. 6. Setup and control form of the beam control block.

DCP Control system of the LANGMUIR station (SEC “SYSTAL” ltd.)

Synchronization

DSAF1000

XFPIPS

Data

Control Data

Control BSXD

Radiation shielding Fig. 7. Organization scheme of the control automation system of the Xray fluorescence experiments.

To solve the problem of synchronizing the ACS and measuring equipment of other manufacturers, the sys tem has two types of synchronization. The first type is electronic via TTLinputs/outputs, and the second type is between the SYSTAL–LANGMUIR ACS control program and control programs of the experi mental equipment by the SYSTAL–Synhro file syn INSTRUMENTS AND EXPERIMENTAL TECHNIQUES

chronization system. In this case, the synchronization system allows one to combine synchronization types for several units and set their sequence. To preliminarily analyze and process results of measurements or adjustment, the graphic analysis module is introduced into the control program. Vol. 54

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KARAICHENTSEV et al. User GUI Visualization module

Data files

Experimental parameter setting

Data preprocessing and saving module

Synchronization module

To the ACS

Control module

API VDM Equipment

Fig. 8. Structure of the control program of Xray fluorescence measurements.

STATION ALIGNMENT AUTOMATION AND REMOTE CONTROL OF THE EXPERIMENT One of the main purposes of the LANGMUIR sta tion is to study selforganizations of organic and bioorganic nanosystems on the liquid subphase sur face [1, 2]. It is planned to use at the station some sur facesensitive Xray technologies, including the method of Xray standing waves at the total reflection condition [4, 5], which implies simultaneous record ing of angular dependences of the mirrorreflected Xray radiation intensity and Xray fluorescence yield intensity. To ensure synchronous recording of the Xray reflection intensity and fluorescence yield for the SYS TAL–LANGMUIR ACS, an additional program unit is created. This is the detector control program (DCP), which controls Xray and fluorescence recording sections based on spectrometric equipment from Canberra Co. The recording systems include an XPIPS energydispersion detector, DSA1000 multi channel analyzer, and a Bicron scintillation detector with a builtin uniSpec multichannel analyzer. The detectors are equipped with a Genie 2000 base spec trometric medium based on the client–server princi ple, allowing one to create their own client applica tions controlling the equipment via the applied pro gramming interfaces (APIs) granted by the Genie 2000VDM (virtual data manager) server part. To record angular dependences of the experimental data, the DCP synchronizes operation of the step motors and the station units ensuring variations in the angle of incidence on the sample, which are controlled by the main SYSTAL–LANGMUIR ACS. Figure 7

shows the organization scheme of the control automa tion system for Xray fluorescence experiments. Functionally, the program consists of the following modules (Fig. 8). The user’s graphic interface: (i) grants users forms and dialog windows for adjustment and control of detectors; (ii) selects the exposure time; (iii) allows one to preset parameters for data acqui sition; (iv) selects ranges of spectrum channels (regions of interest), in which integration will be performed; and (v) includes the experiment visualization system for displaying information on the current detector state, visualizing the spectrum acquisition process, and plotting angular dependences of the mirror reflected Xray radiation intensity and Xray fluores cence yield during the experiment. The control module directly monitors and controls the recording sections and performs: (i) synchronous and asynchronous control and col lection of data from Xray fluorescence and Xray reflected/diffracted signal recording sections; (ii) operation in singlemeasurement mode, and execution of the START, STOP, PAUSE, SAVE DATA, and CLEAR MEMORY commands; and (iii) operation in the synchronization mode with the LANGMUIR station ACS. The synchronization system is realized on reading and rewriting two “expanded” text files, each of which may contain “0” or “1.” Depending on the value read in one of the files, the program makes a decision on the start of its operation or waiting for the end of operation of the step motors. When the operation starts, DCP


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Xray reflection 100

10–1

10–2

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Fig. 9. Measured angular dependence of the intensity of Xrays mirrorreflected from the NiC multilayer synthetic structure at the LANGMUIR station.

writes into the file a wait character for the LANG MUIR station ACS, and, when data acquisition comes to the end, the DCP writes into file a permis sion character for the ACS operation. The data saving system collects and preprocesses data, creates data arrays, and writes them into files for: (i) spectra of energydispersion and scintillation detectors at each experimental point both as text files and as binary files in the Genie 2000 internal format; (ii) a text file with angular dependences of recorded signal intensities, integrated over the specified regions of interest; (iii) for creating and saving (for each detector) a text file containing a twodimensional array represent ing an angular spectrum distribution picture; and (iv) saving parameters of the experiment. Figure 9 shows the measured angular dependence of the intensity of X rays mirrorreflected from the NiC multilayer synthetic structure at the LANG MUIR station. CONCLUSIONS The analysis of the SYSTAL–LANGMUIR ACS operation at the synchronous station shows that the functional–modular principle in building the equip ment and software makes it possible to efficiently solve problems of the station alignment and experiment automation. The parameterization of control objects INSTRUMENTS AND EXPERIMENTAL TECHNIQUES

ensures their formalization, which in turn facilitates embedding of the ACS modules into experiment auto mation systems. The used intelligent controllers placed in the final chain of the experimental equip ment facilitate programming of the user’s interface and significantly increase the reliability of the ACS operation on the whole. In new development works, the authors actively use server functional–modular services (applications) and staticlink libraries for writing client applications operating with control ele ments, operation of which is supported by the intelli gent controllers. Another positive aspect related to formalization of the control objects is the possibility of saving and mul tiply using the parameters and setups of the equipment (equipment configurations) for particular experi ments. The designed user’s multiwindow interface allows different users to work at the station. Experimentalists do not need to study any commands for controlling mechanisms and units to prepare the experiment. It is sufficient to use the setup parameters, execution but tons, and libraries of experimental problems (one dimensional, twodimensional, etc.), based on earlier created and edited job lists. The system of external ACS synchronization with the research equipment, built into the task patterns, is intended to realize by program a queue and synchronism in the execution of the experiment by the measuring module with the pro gram module controlling the Xray optical elements of Vol. 54

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the station. Thus, the SYSTAL–LANGMUIR ACS makes it possible to completely automate the prepara tion and performance of the experiment at the LANGMUIR station. REFERENCES 1. Tereshchenko, E.Yu., Lider, V.V., Zheludeva, S.I., et al., Journal of Surface Investigation. XRay, Synchro tron and Neutron Techniques, 2004, no. 7, p. 5.

2. Lider, V.V., Tereshchenko, E.Yu., Zheludeva, S.I., et al., Journal of Surface Investigation. XRay, Synchro tron and Neutron Techniques, 2004, no. 7, p. 15. 3. Kuznetsov, M.G., Karaichentsev, V.G., Mozgin, A.A., and Chistyunin, V.F., Abstracts of Paper, VII Nat. Conf. “XRay Synchrotron Radiation. Neutrons and Electrons for Study of Nanosystems and Materials. NanoBioInfo Cognitive Technologies, 2009, p. 590. 4. Zheludeva, S.I., Novikova, N.N., Konovalov, O.V., et al., Mat. Sci. Eng.: C, 2003, vol. 23, no. 5, p. 567. 5. Bedzyk, M.J., Bilderback, D.H., Bonmmarino, G.M., et al., Science, 1988, vol. 241, p. 1788.


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