gaussian tel gun progress v. kamerdzhiev, g. kuznetsov, v. shiltsev larp collaboration meeting 10...
TRANSCRIPT
Gaussian TEL gun progress
V. Kamerdzhiev, G. Kuznetsov, V. Shiltsev
LARP Collaboration Meeting 10Danfords on the Sound, Port Jefferson, NY, April 23-25, 2008
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 2
The e-gun designThe electrode geometry is optimized for generating Gaussian-like transverse current density distributions (profiles) using SuperSam/UltraSam code*
* M. Tiunov, INP Novosibirsk, Russia
anode
control electrode (CE)
cathode
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 3
The electron gun
assembled on a6 ¾ conflat flange
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 4
The test bench
gun solenoid
main solenoid
collector solenoid
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 5
Profile measurement technique
I = const
the deflector current is ramped in small steps
at every stepthe probe currentis recorded
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 6
Electron beam analyzer
0.2 mm hole the current probe
ADC PC
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3D current density distribution @ 8kV
-4 -2 0 2 4
-4
-2
0
2
4
Horizontal deflector current (A)
Ve
rtic
al d
efle
cto
r cu
rre
nt (
A)
0.010000.088440.16690.24530.32370.40220.48060.55910.63750.71590.79440.87280.95121.0301.1081.1871.265
-4
-2
0
2
4
0.0
0.3
0.6
0.9
1.2
-4
-2
0
2
4Pro
be v
olta
ge (
V)
Verti
cal d
efle
ctor
cur
rent
(A)
Horizontal deflector current (A)
Ucath
= -8kV
Uce
= -8kV
Uanode
= -8.35kV, Gnd
Bgun
= 1.5kG
Bmain
= 2kG
Bcol
= 1.5kG
F = 65HzPW = 4s
Gaussian electron gun0.4'' cathode
Current densitydistribution
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 8
Profiles vs Uce @ Ucath= 5kV
-5 -4 -3 -2 -1 0 1 2 3 4 5
0.0
0.5
1.0
1.5
2.0
2.5
P
robe v
olta
ge (
V)
Vertical corrector current (A)
-4.6kV -4.7kV -4.9kV -5kV -5.2kV -5.4kV
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 9
Maximum ratings
-2.0x10-6 0.0 2.0x10-6 4.0x10-6 6.0x10-6 8.0x10-6
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Ele
ctr
on c
urr
ent (A
)
Time (s)
Imax
= 1.65AU
cath= U
ce= -10kV
Uanode
= -Ucath
, Gnd
Ucath = -10kV; Uanode = Ucath, Gnd; Ipeakmax = 1.65A; @ Bgun = 4kG; 5*10-9 Torr
The rise/fall time is defined by the driver circuit. Applying positive voltage to the CE in respect to the cathode will result in higher peak electron current
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 10
Summary
• The Gaussian electron gun was successfully tested on the test bench at up to 10kV
• What to do next– install the Gaussian e-gun in one of the TELs– since the e-p beam alignment is very critical we need
to figure out the best way to achieve/maintain optimum e-p alignment
• the Digital Tune Monitor seems to be the best candidate capable of detecting the tune spread change (work in progress)
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 11
Backup slides
• proposed hollow electron beam for LHC collimation system– e-gun simulations are performed using UltraSam code – simulations done by L. Vorobiev– mechanical considerations by G. Kuznetsov
• goals– keep the transverse electron energy low– extract as much current as possible– simulate e-beam compression in solenoidal magnetic field
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 12
Hollow e-beam for LHC collimation system
cathode
near cathode electrode
control electrodeanode
cylindrical symmetry
current density distribution (profile)
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 15
Simulated profile comparison
-30 -20 -10 0 10 20 30
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
cu
rrent densi
ty (
A/c
m^2
)
R (mm)
the proton beam passes through the zero e-current area
V. Kamerdzhiev for BBC team Gaussian TEL gun progress 16
Summary
• the “hollow” gun can be simulated with the tools we have (Super/Ultra SAM)– first look shows promising results
• mechanical design looks doable
• the infrastructure for testing the gun (once it’s been built) is available
• we plan to continue the development and demonstrate the detailed design