THE ON-LINE BEAM CONTROL AND DIAGNOSIS SYSTEM OF TARN
M. Takanaka, S. Watanabe, K. Chiba, T. Katayama, A. Noda and M. Yoshizawa
Institute for Nuclear Study, University of Tokyo

The computer system was used for data logging of accelerator parameters
to underst.and the operation algorism at the beginning. Nowadays, once thebeam succeeds in multiturn-injection into the ring, it stably continues tobe injected and turned. The skill and algorism to find the optimum opration
point has been established. As experiments for accelerator physics haveincreased .in TARN, importance of usage of the computer network is going to movefrom beam control to beam diagnosis.
Computer Network
The TARN computer network has been developed and it now consists of twominicomputer systems (HP-1000 and PANAFACOM U400), the central computer (FACOM
Ml80 IT AD) and several microcomputers, as shown in Fig. 1. The network is
constructed so that each of computer systems of three different ranks may
organically perform its own full capability and may use other computer resources. Task access is designed to be able only both at the monitorscope terminalof the TARN operation console and at graphics terminal of HP-1000, after IPLof each computer.
The main interfacing with external equipments and instruments is madethrough CAMAC system on U400 side, except modules in PANAFACOM ICU (InterfaceCircuit Unit) used for the data logging of accelerator parameters. At present,
the CAMAC system consists of two crates. It enables the data acquisition fromany modules anywhere at the interval of time shorter than 10 m sec. Further,
the installation of an auxiliary crate controller with a microprosessor (ACCM)
provides much faster data acquisition time than 10 v sec. On the other hand,
HP-1000 system is connected to external devices via HP-IB line Hhose merit is
the fact that most of RF measurement and control devices and other instruments
for high precision measurement include such interfaces in commertial base.
Two kinds of graphics terminals are used as interactive input/output
devices, which .are main man-machine interfaces between the operator and theTARN computer network. The operator selects a task number, whose task will beexecuted, among the menu of registered tasks displayed on the CRT's, andenters it from the keyboard. The tast is executed under a respective task-management task at U400 and at HP-1000. Tasks on HP-1000 initiate those of U400
to make communication with them. Tasks on U400 can initiate those inMl80 IT AD, too. At present, task initiation from U400 is not adopted for
HP-1000.
Several request keys of the operation console are assinged to initiationof particular tasks on U400 side for data logging of various parameter groups.
Microcomputers are distributed for the TARN local control systems inorder that each one performs a single allocated task to reduce a heavy loadon minicomputers. They are single board type microcomputers without softwaredevelopment tool. The load modules are developed with U400. Their down-lineloading and initiation are carried out by individual tasks of minicomputers.
Beam Control and Diagnosis
The TARN computer network is used for various purposes. At first, it
was used mainly for voltage pattern generation of RF and data logging ofaccelerator parameters. However, as the study of accelerator physics
proceeds at TARN, more quantitative data are needed and fast data acquisition
is required, which necessarily leads to utilization of a computer. Now almost
all beam diagnoses are made with the use of the computer network.
Recently, a CAMAC gate function generator was developed with a 10 Mhz
clock. It provides a series of trigger or gate signal for an input external-353-

trigger signal. Timing signal is designed as what we want by cascade-connection of these modules. Due to addition of this function to the existing
manual timing controller, it becomes easy to change injection times, RF stacking times, interval time between injections. It becomes possible to supply
fine synchronous tigger or gate signals for data acquisition of beam diagnosis,too.
The apparatus for the emittance measurement is located about 10 m upstream
from the injection position of the TARN. There are eight elements (four quadrupole magnets, two bending ones, and two electrostatic inflectors) between themonitor and the injection position. Results of the emittance measurement andlogged data of the elements are transferred from U400 to the central computer
Ml80 IT AD, where the desirable parameters of elements are searched. Obtained
results are sent back to HP-1000 through U400. The elements are tuned withaid of the central computer.
TARN has eight straight sections named Sl to S8 along the beam stream fromthe beam injection section. For the first tuning of the injection orbit,single rod monitors at Sl, S3 and S6 are used under CPU control, as well as
multi-wire profile monitors of manual operation at S2 and S8. They are used
for observation of the radial position of the single turn beam and the fourturn beam when Q-value is tuned to be 2.25. Next in order to tune the parameters on the multiturn injection, the signal of the electrostatic beam monitor
at S3 and S6 are referred to on the oscilloscope. The survival of the beam forlong time over one second is confirmed by the measurement using the scintillation monitor at 57.
The RF stacking into the longitudinal phase space is performed by a repetitive stacking method. The function generation of RF voltage and frequency
sweep is carried out by HP-1000 and TK-80 CPU network. The operator can
provide a set of the programmed functions of defferent parameters with HP-1000.
Shacking hands with HP-1000 for data handling, TK-80 supplies the programmed
function through DAC to the RF system synchronously with the trigger signalfrom CAMAC gate function generator.
The RF stacking experiment is carried out to analyse the dependence on
the RF voltage and sweep functions, and the capture frequency in pursuit of
the high stacking efficiency. A scintillation monitor is used to measure theradial beam profile. A permalloy monitor with long time constant (~1 sec)
is used to measure beam intensity during the stacking process.
As the preparatory work for the construction of a stochastic coolingsystem at TARN, obsrevation of Schottky signal is performed. Due to the developement of a beam diagnostic system with a spectrum analyser linked to thecomputer network, it has become possible to measure the Q-value without disturbing the beam in TARN.l)
Reference1) A. Noda et al., contributed to thesymposium.

Fig. 1-354-

TARN computer network