1. TPS pulse magnet measurement
Yun-Liang Chu
Magnet Group, NSRRC
Good Afternoon ,
I am YUNLIANG CHU from magnet group. Today I am presenting the magnetic field measurement of pulse magnets.

2. Outline Introduction Measurement system Kicker magnets Septa magnets
Summary
Thats my outline, I will introduce where the pulse magnet installed.
And measurement system, kicker, septum,
In the end, I will make a summary of measurement result.

3. Introduction Top view of TPS
From top view of TPS, the booster and storage ring are concentric circles.
We can magnify this part,

4. Introduction Top view of TPS
From top view of TPS, the booster and storage ring are concentric circles.
We can magnify this part,
Electron beam from linac to booster via 1 septum and 1 kicker, inject into booster and then go around.

5. Introduction Top view of TPS
From top view of TPS, the booster and storage ring are concentric circles.
We can magnify this part,
Electron beam from linac to booster via 1 septum and 1 kicker, inject into booster and then go around.
The booster extraction with 1 kicker and 2 septum via transfer line.

6. Introduction Top view of TPS
From top view of TPS, the booster and storage ring are concentric circles.
We can magnify this part,
Electron beam from linac to booster via 1 septum and 1 kicker, inject into booster and then go around.
the booster extraction with 1 kicker and 2 septum via transfer line
Enter the storage ring injection, there are 2 parts, one is original electron in storage ring will be kicked out by K1 and K2,
And then combine with the other one from this two septum, they will be kicked together by K3 and K4.
That is storage ring injection system.

7. Measurement system
The frequency of the pulse signal is too fast to use Hall sensor, so we make the coil to induct voltage instead.
V=nA dB dt → B= 1 nA Vdt
n：number of coil turns, A：area of coil, B：flux of magnetic field, V：inductive voltage
To display the waveform, the passive RC integrator and a digital oscilloscope are applied. →
And then, we talk about measurement system.
照念 ( 20 to 70 Hz )
-----
According to Faraday’s law of induction, and to integrate of time, we can derive this function. 照念
照念 including resistor and capacitor

8. Measurement system
The function generator trig HVPS and digital scope, respectively.
A CT between power and magnet can show the input waveform, and also connect to the digital scope.
Through pre-amplifier and passive integrator, we can use the coil to measure the signal of magnetic field from pulse magnet.

9. Measurement system Search coil Long coil Downstream SR septum
upstream SR septum
upstream SR kicker
We have two kinds of coils, search coil and long coil.
The first, search coil is made of wire width 0.5mm to wing diameter 5mm for 30 turns, it can measure the distribution of space.
Long coil is to electroplate the path of electron on the PCB plate, and we change the BNC cable to measure the transverse axis.
The 3 picture is to measure septum and kicker
This two plates, one is main field, the other one is leakage field, and that is shielding to reduce leakage field. We will present that later.

10. Kicker magnets Pulse Magnet Type BR Injection BR Extraction
SR Injection
Energy (GeV)
0.15 3
Gap (mm) 21 18 37
Current (A)
250
353
2150
Kick angle (mrad)
15.6
2.6
4.5
Field (T)
0.015
0.0245
0.0715
Iron length (m)
0.5
0.5*2
0.6
Pulse shape
flat top
half-sine
Rise/fall time (ns)
1080
360 -
Flat top (ns)
200
860
Duration (μs)
1.2
1.22
5.2
Voltage (kV) 14
18.6
6.7
Inductance (μH)
2.3
2.7
That’s the kicker table
念以下2圖
Both two kinds of booster kicker are in-vacuum, and the pulse shape is flat top, different from storage ring kicker which has half-sine waveform.
And we also could find the angle that the small energy is easier to kick electron than large energy.
The coil we make only one turn could reduce Inductance.
All the body of kickers are made of ferrite.
We can see the picture, current-field integral curve, the slope remains linear, so it haven`t been saturated.

11. Kicker magnets Booster Injection Kicker
1. flat top 200 ns, flatness ±1%
2. fall time 1080 ns
Booster
Injection
Kicker
homogeneity 0.3 % in good field region 32 mm
b0L = 8610 G-cm
bend 15.6 mrad
This picture shows the output waveforms of kickers for booster injection and extraction from a current transformer.
We take a look the black line booster injection kicker, this waveform has been modified.
照念 flat top two hundred nanosecond, flatness plus and minus 1 percent, fall time over 1 thousand nanosecond.
The fall time is important for injection system. It is smooth, and has few tail ripple.
Besides, the bunch length is 160ns in TPS booster, so we just use the flat top 200ns with flatness plus minus 1%, it could be successful.
右兩圖照念
Consider small energy, this field integral can bend this angel enough.

12. Kicker magnets Booster Extraction Booster extraction kicker Kicker
1. flat top 860ns, flatness ±2%
2. rise time 360 ns
Booster
Extraction
Kicker
homogeneity 0.3 % in good field region 32 mm
b0L = G-cm
bend 2.6 mrad
The red line is the input waveforms of kickers for booster extraction from a current transformer.
照念 flat top eight hundred sixty nanosecond, flatness plus and minus 2 percent, rise time over three hundred sixty nanoseconds.
The rise time is important for extraction system.
右兩圖照念
can bend two point six mrad

13. Kicker magnets Storage ring Injection Kicker
homogeneity 0.1 % in good field region 40 mm
There are four storage ring kickers, K1 to K4, 照念 duration five point two microseconds. And the ferrite length is o point six meter.
右兩圖照念it is better in field homogeneity because is has large pole width.
can bend four point five mrad enough
Storage ring injection kicker
duration 5.2μs
ferrite length 0.6m
b0L = G-cm
bend 4.5 mrad

14. Septum magnets Pulse Magnet Type BR Injection Septum type A
Septum type B(C)
energy (GeV)
0.15 3
gap (mm) 22 15 14
current (A)
2255
8310
8755 (8565)
bending angle (mrad)
209.44
55.5
62.8 (76.8)
field (T)
0.128
0.685
0.818 (0.766)
iron length (m)
0.8
0.8 (1)
pulse shape
half-sine
Duration (μs)
300
voltage (V) 85
340
387 (400)
inductance (μH)
1.95
2.85 A B
That’s the table for septum.
念以下三圖
All the septum are similar, with half-sine waveform, out of vacuum, duration 3 hundred microseconds.
We can also see the slope of the current-field curve are still linear, so haven`t been saturated.
It is important that How to improve leakage field with shielding

15. Septum magnets Cross-section of septum Direct drive type (top view)
The core magnets are built from silicon steel (35CS550) with lamination 0.35 mm.
Coil plate thickness 1 mm, height 98 mm and length 890 mm
One layer and two parts of μ-metal (Netic S3-6, thickness 0.7 mm) for shielding to reduce leakage field 照念

16. Septum magnets Distribution of leakage field along booster orbit
The leakage field change with time.
peak (15 G-cm) at the time of injection
Booster
Injection
Septum
we can see the similar half-sine waveform, and the right side picture is the distribution of leakage field along booster orbit.
The max. leakage field is at about 4 hundred mini meter where is the place of the closest distance.
And there are some other device so that it is difficult to shield this part
左下圖，so we take the peak fired time,照念

17. Septum magnets Distribution of leakage field along electron orbit
The leakage field change with time.
peak (18, 52 G-cm) at the time of injection
Septum A
OK we focus on septum type A, gap 15 mm.
the electron orbit is closer to magnet, so the leakage field is increased.
There are black and red 2 lines means 2 orbits, the black one is the orbit of electron which is kicked out from storage ring, the red line is original orbit which has been stored in storage ring.
So the stored orbit is far little bit.
左下圖照念

18. Septum magnets Distribution of leakage field along electron orbit
The leakage field change with time.
peak (5, 12 G-cm) at the time of injection
Septum B
Septum B is downstream of extraction, upstream of injection. I mean septum B is much farther than A.
So, leakage field of septum B is small even it can bend large angle.
左下圖照念

19. Summary
The kickers for the booster and storage ring were measured at the particular nominal current to have homogeneity 0.3 % and 0.1 % in the transverse direction, 34 mm and 40 mm, respectively.
The leakage field of septum along the beam trajectory was less than 0.01% of main field after shielding.
The pulsed magnet system will be optimized continuously in the future. 照念
1.5*10^-4= 0.01% Ten to minus two percent
Thank you very much

20. Thank you for your attention