OBSERVATION OF COLLECTIVE RESONANCE STOPBANDS IN SIMULATOR FOR PARTICLE ORBIT DYNAMICS

S. Ohtsubo, M. Fujioka, H. Higaki, K. Ito, K. Izawa, M. Kuriki, H. Okamoto, K. Tanaka

Graduate School of Advanced Sciences of Matter, Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8530

Abstract

We have designed and constructed a compact non-neutral plasma trap system to study various collective effects in space-charged-dominated particle beams. The tabletop apparatus is called “S-POD (Simulator for Particle Orbit Dynamics)” that consists mainly of a radio-frequency quadrupole trap, several diagnostic systems, a vacuum system, a data-taking computer, and a number of AC and DC power supplies for control of the plasma confinement potential. In the present experimental study, S-POD is employed to demonstrate the existence of linear and nonlinear collective resonance stopbands that depend on various machine parameters. To simulate lattice-dependent effects on the stopbands, we apply periodic perturbations to ion plasmas and confirm the excitation of additional resonances. We also observe the shifts of stopbands caused by the collective space-charge force.

1998

ふ

[1,2]

“S-POD (Simulator for Particle Orbit Dynamics)” スゝ [3] S-POD

さ々 ゝ

┷㎲ ″

ゝ㍂ 20cm

(MCP) 406 mm┷

┘

″

40Ar+

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├├

ゝ㍂

S-POD セ

ふ

Proceedings of Particle Accelerator Society Meeting 2009, JAEA, Tokai, Naka-gun, Ibaraki, Japan

121

ぜ

┘

よSacherer[4] Gluckstern[5]

smooth approximation1 [6]

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= n / 2 (1)

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mn

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"m# m($0 %C

m&$). (2)

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スゝ

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1

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"0#Cm$" % N sp &

n

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┘ ㎰ 2Ⅴ

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1/ 4

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[2,3] LabVIEW

々

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3

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㈻

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FODO93 V 0.5

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4 1 249 kHz

1 msec

12FODO 83 kHz83 ┞

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N sp = 12

ふ

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ぜ (3)

!

"0#C

m$" % 6n / m

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"0

3

!

m = 2

!

"0

2

!

m = 3

ふ

Proceedings of Particle Accelerator Society Meeting 2009, JAEA, Tokai, Naka-gun, Ibaraki, Japan

122

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N sp = 3

0.5% 1.0% ス

!

N sp = 12 ふ

ぜ

!

"0

0.8 1.6

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m$" % 3n / 2m

!

m = 2

4

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m = 4

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!

N sp " (n / 2m)

1 msec ゝ

(3) ↓

3Ⅴ

(3)

!

Cm

!

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m[4,6]

!

C2

0.75

!

Cm

m1 ふ

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ふ

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さ

ぞ

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S-POD

1000

┞

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S-POD

[1] H. Okamoto and H. Tanaka, Nucl. Instrum. Meth. A 437

(1999) 178. [2] H. Okamoto, Y. Wada, and R. Takai: Nucl. Instrum. Meth.

A 485 (2002) 244. [3] R. Takai, H. Enokizono, K. Ito, Y. Mizuno, K. Okabe, and H.

Okamoto: Jpn. J. Appl. Phys. 45 (2006) 5332. [4] F.J. Sacherer: Ph.D. Thesis, UCRL 18454 (1968). [5] R.L. Gluckstern: Proc. Linac Conf. (Fermilab, Batavia, IL,

1970) p.811. [6] H. Okamoto and K. Yokoya: Nucl. Instrum. Meth. A 482

(2002) 51. [7] R. Baartman: AIP Conf. Proc. No. 448 (AIP, New

York, 1998) p.56.

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