L1S Jitter with AIP Modulator

Franz-Josef Decker 25-Sep-2014

L1S Phase Jitter History

• 0.04 deg 0.07-0.12 deg it is bad now• TDLY: Modulator pulse cuts into RF pulse• HV higher and then better jitter is new!

July 2014 Sep. 2014

HV: 300 320 kV

TDLY: -5.7 -4.2 us

L1S HV Scan

• AIP modulator “allows” it

300 kV 340 kV

Pha

se J

itter

[de

g]

AIP SCR Modulator Upgrade(before and after)

• L1X shows similar behavior to L1S• Looks like timing jitter July 2014 Sep 2014

L1S

• Lost

July

Sep.

Best for Sep

More L1S

• Reminder: 100 ppm 0.05 deg

Lowest timing jitter Maybe thyratron worse

Thyratron back swing jitter

• It shouldn’t have this two state

L1S is Main Source of DL2 E-Jitter

• L1S phase is nearly 75% of energy jitter power, (DE/E = 0.025 0.057 %)

• And phase is 86 % correlated to HV

Pha

se

d

eg

HV counts

86 %

Summary• New L1S modulator and Klystron setup is

2-3 times worse• It “seems” to point to SCR switched AIP

upgraded modulator• Many more variations happened: new thyratron,

30120 Hz, -50 -75 V thyratron bias change, filter in trigger bypassed, LC for DQ-ing, Ross devider, …

• To do: Secondary power supply, …