JAERI-Conf 95-021

PA07Study of ECRIS for highly charged ion production- HiECR MK3T. KATAYOSE, H. TOMIZAWA, K. ISOKAWA and T. HATTORI
Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology
Meguro-ku, Tokyo, Japan

1. Introduction
The former HiECR had good performances in 6
and 10 [GHz] operations, while in the case of 14 [GHz]operation, the intensity of highly-charged heavy ions
was very low [1,2,3). It seemed that the result was dueto the narrow gap(3[mm] or less) between the surface ofECR zone and that of the chamber wall.
HiECR MK3 has been designed to produce strong
axial mirror field and radial hexapolar field enough to 14[GHz) operation.
The HiECR MK3 was constructed and operated forthe first time.

0100200
3000[mm]

2. HiECR MK-3Fig.l.
The former HiECR had been operated with themicrowave frequency 6 or 10 [GHz). Therefore some
improvements were required so that the MK3 can beoperated at 14 [GHz]. The number of mirror coils has
ad:led up to 9 (MK2: 7), the plasma chamber has been
modified and the hexapole has been made newly.
Schematic view of HiECR MK3 is drawn in Fig.1 andmain parameters are shown in Table.l.

100200300400[mm]Schema of HiECR MK-3

3. Magnetic Field
radial hexapoler field

Radial hexapoler fields were measured along the axisand radius(Fig.2). The value is 13.1[kG) at the chambersurface.

Table I

Main JXlrameters of HiECR (MK-3) Ion Sources
Microwave frequency
Diameter of chamber
Hexapole magnet
hexapole field on surf.
material
inner diameter
lengthMirror coils
no. of coilsmax. current
max. power1470[GHz)[mm]

13.1[kG]
Nd-Fe-B
76[mm]
145[mm]9600
57axial mirror field

We measured the axial mirror field through theaxis(r=O) with mirror coils current 600[A). The result isshown in Fig.3.
ECR zone
The magnetic field components (B7 ,B8 ,B,_) at aposition (r, 8, z) in the cy Iindrical coordinates is the[A)[kW)

following.

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Br = By sol + B/zex
hex

Be = Be

12B _ B sol + B hex

z- z

105..:..:: 8.........
'"' 6~cham. surf

The closed surface

440302010r[mm] (z=O[mm])

IBI =me wrf je is called ECR zone

and electrons are accelerated in this surface.
From the radial and axial field measurements, theaxial size of the ECR zone is 78[mm] long and thediameter is 36[mm](the gap between the surface of ECRzone and that of the chamber wall;17[mm]).

200

z3. First operation

6ooo 00

p le edgeooo

5Fig.4 shows a Ne ions spectrum obtained at the first
14 [GHz] operation. Wide peaks exists on right sides ofevery charge-state peaks. These seemed to be produced by
the ions which had captured an electron in acceleration
gap(Fig.S). The vacuum must be improved after this.

00405o3~'"'0020/J•WOVC

10Nc; 0.2 x 10'6Torr

20080 100 120 140 160(r=23[mm])

40 60
Z[mm]

Radial hexnpoler field

Fig.2.

Fig.4.

[kG] r-10 r111-0 000

5111'--vv-'--I,\)
I0II0•0{\ 00270W

5.7 X 10'6 Torr

00'oo 0 0 0 ' - - ' -I Hex. I rII10018GHz14GHz

0{\III200III30000III400[mm]axial mirror field distribution(mirror coilscurrent 600 [A])Fig.3.

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20Ne ions spectrum

JAERI-Conf 95-021

4. Plasma volume and shape effect
fu general, +q charged ions current extracted from aplasma with volume Vis following [4].
n qeV
1=-q__•q

As concerns ECRIS, this relation is more complex

because of influences of the anode position and the anodehole size and so on.
The new hexapole does not have return-yokes and it
is covered with SUS and the surroundings of SUS are
insulated by ethylene chloride.
Solenoid coils for adjustment of plasma volume are
been possible to set around the new hexapole because ofnothing of return-yoke. By varying the diameter of ECRzone, we will investigate the best plasma shape togenerate highly-charged ions.

References[1] T. Hirata, T. Hattori, M. Sekiguchi, Y. Ohshiro, .M.
Oyaizu, Y. Yamashita, A Kitagawa and T. Ishii :Pro. of 8th Symposium on Accelerator Science andTechnology, 8(1991)p.p.82-83.
[2] T. Hattori, M. Sekiguchi, A Kitagawa, Y.
Yamashita, Y. Ohshiro and T. Hirata :Pro. of 11thWorkshop on ECR Ion Source, 11(1993)p.p.182186.
[3] M. Sekiguchi, Y. Ohshiro, Y. Yamashita, Y. Isoya,
T. Hattori and A Kitagawa: Pro. of 11th Workshop
on ECR Ion Source, 11 (1993)p.p.46-51.
[4] D. Ritz, G. Melin, M. Pontonnier and T.K.Nguyen :Pro. of 11th Workshop on ECR Ion Sources,11(1993)p.p.46-51.

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