PERFORMANCE OF THE INS RFQ LINAC 'LHL"
A . I t a n o ，T.Nakanishi, S.Arai 9 T.Hattori 9 T .Fuk us hi m a , Y.Sak urada 5 T.Honma,
N.Tokuda9 S.Yamada, M.Takanaka ，A.Mizobuchi ，Y.Hirao and N.Ueda
Institute for Nuclear Study, University if Tokyo
Tanashi ，Tokyo 188 ，Japan*National Institute of Radiological Sciences
Anagawa, Chiba 260, Japan

ABSTRACTThe radio-frequency quadrupole (RFQ) linac 1LITL■was constructed andaccelerated ion beams of H+ ，

^He+ , ®Li+ and \ i + . The linac was designed

to accelerate particles with charge to mass ratio (q/A) of 1 V I /7 injected at
5 keV/u up to 138 keV/u. The acceleration cavity of four vane structure with
100 MHz resonant frequency is 56 cm in diameter and 138 cm in length.
Transmission exceeding 90% was obtained for proton beam ：of 80 uA. Theacceleration characteristics agreed well withthe computer simulation by PARMTEQ

To accelerate \ i + ions，an rf power of 22 kW was fed with a loop coupler in
cw operation, where an electric field of 205 kV/cm was applied on the vanes.
This corresponds to 1.8 times the Kilpatrick’s criterion at 100 MHz, A maximum
field of 2.0 times the criterion was achievedin pulse operation with 5ms

width and 25 ms repetition period,
1 2

The radio-frequency quadrupole (RFQ) linac 5 has the following advantages;
1 , A low voltage injection is possible without lowering a space charge limit.
2, An ability of adiabatic bunching results in capture efficiency exceeding 90%
and minimal loss of input dc-beam.
3 4 5 6 7
8
Based on the studies on beam dynamics design ， ’，5 9 machine structure
Table 1 . Parameters of the INS RFQ Linac LITL.
Ion
Injection Energy
Output Energy
Operation Frequency
Normalised Emittance at Input
Vane Length
Number of Cells
Characteristic Bore Radius
Minimum Bore Radius
Focusing Strength
Maximum Defocusing StrengthIntervane Voltage for q / A = 1/7
Maximum Field
Transmission for q / A = 1/7

r0Aoq/A = 1 〜 1/7
5 keV/u
138 keV/u
100 MHz0-6тг mm-mrad
122.3 cm132
0.41 cm
0.25 cm
5.0-0.11

62 kV
205 kV/cm
94% ( 0 rnA)
92% ( 2 mA)
64% ( 1 0 mA)

and rf system of RFQ linac, we have constructed the RFQ linac 'LIT い . The
parameters of LIT し are given in T able. I.

F i g . 1 shows the acceleration cavity.

Fig. 2 shows the vane parameters v s . cell number. The detailed description of9
LITL is given elsewhere •Beam test was performed using ion beams of H + ， H ” H = ， ^He+ and 0 ，4 i + .
Momentum spectra for the ion beams accelerated at the designed values ofintervane voltage are shown in Fig. 3.

Fig. 4 shows the momentum spectra of H+

beam for various values of intervene voltage Vn ( normalised by the designvalue)•Fig.

5shows the output current of ion beams as a function of inter-vane v o l t a g e . 卜ig. 6 shows the transmission f o r Hbeam as a function of

normalised intervane voltage V n . Transmission exceeding 90% was obtained.
Singly charged ion beams up to7Li+were successfully accelerated by RFQ

linac 'LITL1. the acceleration characteristics agreed well with the computer
simulation by PARMTEQ.
Acceleration of higher intensity b e a m ， where space charge and beam loading
effects are important, is now under preparation.
buncher

RM shaoerк 十■— и-accelerator-Ц^boos terpreouncner

T31Л

-30

-60

F i g . 1. Schematic drawing of the acceleration cavityof LITL.

-9 0cell no.
MQ .

{.qJл

5The vane parameters of LITL vs, cell number.

(nA)

(nA)

965 keV
I138

I 276

ksVkeV- 3

SLi+s s UI

^

40.4

7Li +

1i,
丨丨丨1I ,52S keV j i+
Ji

Q.3

ll-Js-IndvoVca.
30

145

155

i r !!ii'l丨：!

UCoil Current of BA magnet (A)/• and 3He+ b eams •400!

11, 220

Momentum spectra for H+ ，j!

! n1 丨…
\Mag. current (A)

-оОО^

70

80 70

иа9. Current (A)S° 70

切80h Др/р= 2/o

10Fig. 4 . Momentum spectra forbeams accelerated at the various
intervene voltages (upper) and PARMTEO results (lower).

CJca

召

Intervane Voltage (kV)
丄7+M g ， 5 • Output beam currents of H‘ 〜 Li measured asa function of the intervane voltage. The design values
required for each beam acceleration are indicated by
Vi〜 、ん.

REFERENCES

F ig . 6 . Transmission for H* beam plotted as a functionof the normalized i ntervane voltage.
The s o lid lin eshows calculated transmission and. the broken lin e isthat for non-captured beam.

1 . I.M.Kapchinskij and N.M.Lazarev, IEEE Trans. N u c l . S c i • NS-26，3462 (1979).
2. K.P.Krandal et a l . , Proc. 1979 Linear Acc. Con f . ， Montauk ， U . S . A ,，BNL-51134, 205 (1979).
3. N.Ueda et a l .3 Proc. 1981 Li near Acc. C o n f .5 Santa Fe, U.SLA. эLA-9234-С，(1982).
4. T.Nakanishi et al., INS Report NUMA-30 (1982).
5. N.Tokuda and S.Yamada ， Proc. 4th Symp. Accelerator and Technology ， ICPR ，Wako, Japan (1982).
6. S.Yamada ， Proc. 1981 Linear Acc. C o n f .， Santa Fe, U.S.A.9 LA-9234-С (1982).
7. T.Nakanishi et a l .， P r o c . Symp. Accelerator Aspects of Heavy Ion Fusion ，GSI-82-8 (1982).
8. S.Itoh et a l . , INS Report NUMA-51 (1983).
9. N.Ueda et a l .9 Proc. 1983 Particle Accelerator Co n f . 9 Santa F e ， I L S . A ， （1983).