PHASE LOCK LOOP AND ASSOCIATED COMPONENTS FOR
THE RADIO FREQUENCY SYSTEM OF THE PF STORAGE RING PART-I

H. Kobayaka wa and A.K. Mitra
National Laborato ry for High Ene~gy Physics
Oho-mach i, Tsukuba- gun, Ibaraki- ken, Japan

1.

Introduc tion

The PF storage ring is designed to store 0.5 A electron beams at an
kW forenergy of 2.5 GeV! The synchrot ron radiatio n loss is more than 250MHz),(500
systemtion
acceleraRFTheon.
magnetwigglerthe case withplannedconsisti ng of four 180 kW(cw) klystron s and associat ed systems, aren andradiatio
ronsynchrot
thebylostpower
thetecompensa
todto be installetime.
lifequantum
longa
maintaintoyto give the phase stabilit y necessar
designFigure 1 shows the block diagram of the RF system which is now underpower
low
theofoutline
designabrieflyand construc tion. We describe herelevel RF system. Results of basic tests for the phase lock loop using
3
electron ic phase shifters 2 ' 3 and phase meter are describe d briefly.
2.

Outline of RF control system1) Phasing: to give proper phase combinat ion to each cavity the electronic phase shifters ("¢ 1 " in Fig. 1) are used .for phase adjustme nts
among four RF lines.
the2) Klystron phase lock loop ("KLYSTRON PLL" in Fig.l): to maintainoutput
klystrontheofphasethe,synchron ous phase angle constant
has to be stable against various phase changing effec.ts. (PLL canalso beachiev ed using voltage controll ed oscillat or as describe d inPart-II. )3} Automati c cavity voltage control(" AGC" in Fig. 1): to stabiliz ecavity voltage against beam loading effects etc.
4) Automati c cavity tuning: to compensa te reactive beam loading andeffects due to the temperat ure change. Tuning control is made by thevoltage correspo nding to the phase differen ce between input signal
and sampled signal of the cavity ("TUNER LOOP" in Fig. 1).

3.

Phase shifter/p hase meter/PL L

Electric ally variable phase shifters are to be used as control elements
shifterin feedback loops and to give proper phase angle in the system. Phasetermiof wide variable range was built using varactor diodes employed as theas anating elements of hybrid couplers . Figure 2 shows the phase response
MHz500at
displaypolar
theis3Figurefunction of control voltage.
nshowing 360° phase variatio n with control voltage of 11 volts. Insertions.
deg/100
1waschangephaseofrate
maximum
andloss was about 7 dB
Phase meter which produces de voltage proporti onal to the input phase
klystrondifferen ce, having wide dynamic range was designed and built for theof thePLL and for the cavity tuning loop. Figure 4 gives the block diagram
inputwith±2°
withinphase
thelocktoalbe
iswhichprelimin ary test for PLLphase modulati on of 160° and amplitud e change of 25 dB.

-219-References
1)
2)
3)

Photon Factory Design Manual.
H. Schwarz, PEP Note 283 (1979).
Manufactured by R and K Lab.

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