Nextef status and near future
plan
July 2, 2008
K. Yokoyama, S. Matsumoto and T.
Higo
Nextef RF power line: Nominal value
Low loss waveguide
2-klystrons  120MW, 300ns
klystron—3dB 2.3m
3dB— LLWG 1.5m
LLWG 5m
LLWG—ACC Str 5.0m
WR90 flanges ~36sets*7mm SUS
ACC Structure
92MW
080513-15
Loss Kly.Str. ~23%
Delay ~ 50ns
Two klystrons
120MW
2nd collaboration meeting on X-band
2
Nextef の現状
• パワー計測
– パワー計測の校正を確立し、水負荷や複数台の方向性結合器
間で±10%程度で矛盾なく計測可能になった。
• ピークパワー
– 210nsec、80MW @合成部 → 加速管入力部で~60MW相当
– 300nsec、70MW@合成部 プロセシング中
– 300nsec、80MW達成したら、加速管試験に入る予定
• 放電特定システム
– これから至急立ち上げる
• 現システム、KX03加速管での高電界運転で行う。
• 2週間程度を予定している。
– 最低必要条件
• 各パルスを解析できること。
• 加速管の放電を確実に同定できること。
Nextef: Nominal observables along waveguide
SLAC 3dB
ACC structure
DC made by BINP
WR90
IP 30l/s
Guard window
TE01-type
Higo Presentation at 2nd collaboration
meeting at KEK May 2008
Ohtsuka Load
080513-15
Lounine Load
(based on SLAC design)
2nd collaboration meeting on X-band
4
Nextef inside shield room
basic components are now in line.
2008/4/18
2008年メカワークショップ(肥後)
5
Nextef: observables along beam axis
PM GV
PM
ACC str GV
KX03
VAC
Q-mass
E
VAC DC
FC
Qmass
Varian
IP
VAC
230
WC
Insul
PM
Slit
AM
1 87
GV FC
GV
425
PM
DC
E
H IP
FC
Lounine
IP H load
IP
Varian IP
FC
AM
DC
WC
FC
IP H Otsuka
load
Load
FC
FC
Higo Presentation at 2nd collaboration
meeting at KEK May 2008k
080513-15
2nd collaboration meeting on X-band
6
Nextef Run061108
(From Jun.11, 24Hr/day)
Missions of this run:
•KX03 Acc Structure installed.
•Commission Breakdown Detection system.
•Established 60MW 300ns RF for Acc structure.
What we find are
•Modulator runs pretty well.
•Klystron_N (North side) runs well.
•Klystron_S (South side) sometimes breakdown at gun region.
(One~two per day under 25pps.)
•Vacuum Trips in the area of the power combiner (detailed
location is yet to be identified) and in the Acc structure area.
Nextef History Plots of Current Run
(Starting Jun. 11, KX03 installed.)
Input Power for KX03 (blue) / pulse width (red)
65MW, 300ns, 25pps
As of Jul. 1.
Vacuum: Upstream Acc Str (green) / Down stream Acc Str (pink)
Breakdown detection
• Inhibit the following pulses
– Big jump in symmetric reflection: exists
• Manual threshold setting from time to time
– Vacuum monitored by CCG: exists
• Control power rating following vacuum level
• Threshold is nominally 10-4Pa
– Other monitors
• Faraday cup current: not yet confirmed
– Not yet established, now trying to test with KX03 system
• Light from a guard window monitored by PMT: exists
• X-rays: probably start without it
– Scintillator + PMT
• Acoustic emission: start test without it
– SLAC VME system being recovered,
Pulse analysis
• Every RF pulse analysis: now being implemented
– Four pulses (F, Rs, Ra, T) with DPO7054
– System the same to that of study with narrow waveguide
– Statistical data is acquired
• To get various distribution, such as missing energy
– 10 pulses are recorded
• To see any precursors
• To see following pulses in future?
• Other RF pulses or others: start as is
– Monitored by Tektro oscilloscope
• Breakdown pulse is recorded for off-line analysis
Near future plan
• System power up
– As much as possible with the KX03 structure
– Processing mostly the power distribution system
• Installation of T18_VG2.4_Disk
– By end of this month, as soon as system establishment
• Operation in July and August
– Day-time 9-20 operation by X-band members
– Start 24h operation from September
• Sophistication of the system: being prepared
– RF pulse width automatic control (Aug.)
– Identification of all INTLK information (Sep.)
– Acoustic, X-rays, ……
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