LINAC - Revision history

Rtang: /* Workhorse-Resonator Calibration Procedures */

2022-09-12T22:10:33Z

Workhorse-Resonator Calibration Procedures

← Older revision		Revision as of 18:10, 12 September 2022
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	Or else use phase meter.		Or else use phase meter.

			= LINAC status readout =
			[[File:LINAC readout station.png\|thumb\|right\|LINAC readout station]]

	= Contact =		= Contact =

Rtang at 22:08, 12 September 2022

2022-09-12T22:08:05Z

← Older revision		Revision as of 18:08, 12 September 2022
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	= Contact =		= Contact =
			* David Spingler mailto:dspingler@fsu.edu
	* Lagy Baby mailto:lbaby@fsu.edu		* Lagy Baby mailto:lbaby@fsu.edu
	* Ingo Wiedenhoever mailto:iwiedenhoever@fsu.edu		* Ingo Wiedenhoever mailto:iwiedenhoever@fsu.edu

Etemanson: /* Bunching System: Buncher and Chopper */

2022-08-26T17:19:58Z

Bunching System: Buncher and Chopper

← Older revision		Revision as of 13:19, 26 August 2022
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	[[File:TimeStructureOfTheBunched.png\|500px\|thumb\|right\|Time structure of the bunched and bunched/chopped beam (outdated picture, the pulses are 82.6 ns apart)]]		[[File:TimeStructureOfTheBunched.png\|500px\|thumb\|right\|Time structure of the bunched and bunched/chopped beam (outdated picture, the pulses are 82.6 ns apart)]]

	The d.c. beam from the ion source is bunched into a series of pulses, about 1 ns long and 82.6 ns apart by a gridded buncher at the L.E. end of the tandem, see figures 16 (a) and 1. The residual beam, about 50% of the total, between pulses, is swept away by a parallel plate chopper at the H.E. end of the tandem, see figures 16 (b) ~~and 1~~. Because the beam pulses entering the LINAC must be precisely synchronized with the R.F. in the LINAC resonators, the L.E. buncher and chopper are both actively phase locked to the LINAC 97 MHz master oscillator.		The d.c. beam from the ion source is bunched into a series of pulses, about 1 ns long and 82.6 ns apart by a gridded buncher at the L.E. end of the tandem, see figures 16 (a) and [https://fsunuc.physics.fsu.edu/wiki/index.php/FSU_Fox%27s_Lab_Wiki#Layout_of_the_Laboratory Laboratory Layout]. The residual beam, about 50% of the total, between pulses, is swept away by a parallel plate chopper at the H.E. end of the tandem, see figures 16 (b). Because the beam pulses entering the LINAC must be precisely synchronized with the R.F. in the LINAC resonators, the L.E. buncher and chopper are both actively phase locked to the LINAC 97 MHz master oscillator.

	The chopper R.F. Is phase locked to the M.O directly. However, this would be insufficient for the L.E. buncher because the transit time of the beam pulses from the L.E. buncher to the LINAC is sensitive to the ion source pre-acceleration voltage and to the condition of the tandem. Instead, the phase of the L.E. buncher is continuously varied to keep constant the time of arrival (or phase) of the beam pulses at the beam phase detector this is located just after the LINAC 90◦ magnet, see [https://fsunuc.physics.fsu.edu/wiki/index.php/FSU_Fox%27s_Lab_Wiki#Layout_of_the_Laboratory Laboratory Layout].		The chopper R.F. Is phase locked to the M.O directly. However, this would be insufficient for the L.E. buncher because the transit time of the beam pulses from the L.E. buncher to the LINAC is sensitive to the ion source pre-acceleration voltage and to the condition of the tandem. Instead, the phase of the L.E. buncher is continuously varied to keep constant the time of arrival (or phase) of the beam pulses at the beam phase detector this is located just after the LINAC 90◦ magnet, see [https://fsunuc.physics.fsu.edu/wiki/index.php/FSU_Fox%27s_Lab_Wiki#Layout_of_the_Laboratory Laboratory Layout].

Etemanson: /* Bunching System: Buncher and Chopper */

2022-08-26T17:17:59Z

Bunching System: Buncher and Chopper

← Older revision		Revision as of 13:17, 26 August 2022
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	[[File:TimeStructureOfTheBunched.png\|500px\|thumb\|right\|Time structure of the bunched and bunched/chopped beam (outdated picture, the pulses are 82.6 ns apart)]]		[[File:TimeStructureOfTheBunched.png\|500px\|thumb\|right\|Time structure of the bunched and bunched/chopped beam (outdated picture, the pulses are 82.6 ns apart)]]

	The d.c. beam from the ion source is bunched into a series of pulses, about 1 ns long and 82.6 ns apart by a gridded buncher at the L.E. end of the tandem, see figures 15 (a) and 1. The residual beam, about 50% of the total, between pulses, is swept away by a parallel plate chopper at the H.E. end of the tandem, see figures 15 (b) and 1. Because the beam pulses entering the LINAC must be precisely synchronized with the R.F. in the LINAC resonators, the L.E. buncher and chopper are both actively phase locked to the LINAC 97 MHz master oscillator.		The d.c. beam from the ion source is bunched into a series of pulses, about 1 ns long and 82.6 ns apart by a gridded buncher at the L.E. end of the tandem, see figures 16 (a) and 1. The residual beam, about 50% of the total, between pulses, is swept away by a parallel plate chopper at the H.E. end of the tandem, see figures 16 (b) and 1. Because the beam pulses entering the LINAC must be precisely synchronized with the R.F. in the LINAC resonators, the L.E. buncher and chopper are both actively phase locked to the LINAC 97 MHz master oscillator.

	The chopper R.F. Is phase locked to the M.O directly. However, this would be insufficient for the L.E. buncher because the transit time of the beam pulses from the L.E. buncher to the LINAC is sensitive to the ion source pre-acceleration voltage and to the condition of the tandem. Instead, the phase of the L.E. buncher is continuously varied to keep constant the time of arrival (or phase) of the beam pulses at the beam phase detector this is located just after the LINAC 90◦ magnet, see [https://fsunuc.physics.fsu.edu/wiki/index.php/FSU_Fox%27s_Lab_Wiki#Layout_of_the_Laboratory Laboratory Layout].		The chopper R.F. Is phase locked to the M.O directly. However, this would be insufficient for the L.E. buncher because the transit time of the beam pulses from the L.E. buncher to the LINAC is sensitive to the ion source pre-acceleration voltage and to the condition of the tandem. Instead, the phase of the L.E. buncher is continuously varied to keep constant the time of arrival (or phase) of the beam pulses at the beam phase detector this is located just after the LINAC 90◦ magnet, see [https://fsunuc.physics.fsu.edu/wiki/index.php/FSU_Fox%27s_Lab_Wiki#Layout_of_the_Laboratory Laboratory Layout].
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	The buncher phase lock system, on its own, woks quite reliably. Unfortunately, the chopper, being located before the phase detector, makes the overall behavior more complicated. If for any reason, the beam pulses do become mis-phased by more than a ns or so, there are swept-away by the chopper and do not reach the phase detector. In this case, the phase detector still sees “pulses”, but of residual beam generated by the chopper instead. A spurious phase error signal is generated and the beam phase lock system may hang up.		The buncher phase lock system, on its own, woks quite reliably. Unfortunately, the chopper, being located before the phase detector, makes the overall behavior more complicated. If for any reason, the beam pulses do become mis-phased by more than a ns or so, there are swept-away by the chopper and do not reach the phase detector. In this case, the phase detector still sees “pulses”, but of residual beam generated by the chopper instead. A spurious phase error signal is generated and the beam phase lock system may hang up.

	To overcome this the “pulser range alarm” unit, when it goes into out-of-lock mode, temporarily disables the feedback control of the L.E. buncher phase, and resets the L.E. buncher phase to that corresponding to zero phase error. In most cases this automatically unhangs the system and allows the feedback system to lock up again. The chopper phase lock system uses an R.F. pick-up signal from the chopper itself and is independent of the beam; see figure 17		To overcome this the “pulser range alarm” unit, when it goes into out-of-lock mode, temporarily disables the feedback control of the L.E. buncher phase, and resets the L.E. buncher phase to that corresponding to zero phase error. In most cases this automatically unhangs the system and allows the feedback system to lock up again. The chopper phase lock system uses an R.F. pick-up signal from the chopper itself and is independent of the beam; see figure 17.

	# Check beam current on BS-2		# Check beam current on BS-2

Etemanson: /* Bunching System: Buncher and Chopper */

2022-08-26T17:16:15Z

Bunching System: Buncher and Chopper

← Older revision		Revision as of 13:16, 26 August 2022
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	The d.c. beam from the ion source is bunched into a series of pulses, about 1 ns long and 82.6 ns apart by a gridded buncher at the L.E. end of the tandem, see figures 15 (a) and 1. The residual beam, about 50% of the total, between pulses, is swept away by a parallel plate chopper at the H.E. end of the tandem, see figures 15 (b) and 1. Because the beam pulses entering the LINAC must be precisely synchronized with the R.F. in the LINAC resonators, the L.E. buncher and chopper are both actively phase locked to the LINAC 97 MHz master oscillator.		The d.c. beam from the ion source is bunched into a series of pulses, about 1 ns long and 82.6 ns apart by a gridded buncher at the L.E. end of the tandem, see figures 15 (a) and 1. The residual beam, about 50% of the total, between pulses, is swept away by a parallel plate chopper at the H.E. end of the tandem, see figures 15 (b) and 1. Because the beam pulses entering the LINAC must be precisely synchronized with the R.F. in the LINAC resonators, the L.E. buncher and chopper are both actively phase locked to the LINAC 97 MHz master oscillator.

	The chopper R.F. Is phase locked to the M.O directly. However, this would be insufficient for the L.E. buncher because the transit time of the beam pulses from the L.E. buncher to the LINAC is sensitive to the ion source pre-acceleration voltage and to the condition of the tandem. Instead, the phase of the L.E. buncher is continuously varied to keep constant the time of arrival (or phase) of the beam pulses at the beam phase detector this is located just after the LINAC 90◦ magnet, see ~~figure 1~~.		The chopper R.F. Is phase locked to the M.O directly. However, this would be insufficient for the L.E. buncher because the transit time of the beam pulses from the L.E. buncher to the LINAC is sensitive to the ion source pre-acceleration voltage and to the condition of the tandem. Instead, the phase of the L.E. buncher is continuously varied to keep constant the time of arrival (or phase) of the beam pulses at the beam phase detector this is located just after the LINAC 90◦ magnet, see [https://fsunuc.physics.fsu.edu/wiki/index.php/FSU_Fox%27s_Lab_Wiki#Layout_of_the_Laboratory Laboratory Layout].

	[[File:BlockDiagramOfBucherElectronics.png\|500px\|thumb\|right\|Simplified Block diagram of buncher electronics (outdated picture, upgrades include using a 12.125 MHz 4-Harmonic Generator and a digital function generator)]]		[[File:BlockDiagramOfBucherElectronics.png\|500px\|thumb\|right\|Simplified Block diagram of buncher electronics (outdated picture, upgrades include using a 12.125 MHz 4-Harmonic Generator and a digital function generator)]]

Etemanson: /* Checking for proper phase lock and field level */

2022-08-26T17:12:06Z

Checking for proper phase lock and field level

← Older revision		Revision as of 13:12, 26 August 2022
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	If the P.D.P. monitor signal shows no resemblance to a square wave (figure 19) (even a ‘smeared’ out one), i.e. the trace is a line at 0V or near 1V, the P.D.P. is not switching.		If the P.D.P. monitor signal shows no resemblance to a square wave (figure 19) (even a ‘smeared’ out one), i.e. the trace is a line at 0V or near 1V, the P.D.P. is not switching.

	[[File:OSCILLOSCOPELOCKSTATUSDISPLAY.jpg\|500px\|thumb\|right]]		[[File:OSCILLOSCOPELOCKSTATUSDISPLAY.jpg\|500px\|thumb\|right\| Figure 19: Top most signal is the P.D.P. monitor signal, the yellow signal in the center is the can monitor and the purple sawtooth signal is the phase error. ]]

	If the P.D.P. is switching, but smeared out, and the phase error signal (figure 19) is smeared out, or is jumping over most of the screen, the resonator is totally out of phase lock -i.e. the resonator frequency does not match the master oscillator frequency, see c.		If the P.D.P. is switching, but smeared out, and the phase error signal (figure 19) is smeared out, or is jumping over most of the screen, the resonator is totally out of phase lock -i.e. the resonator frequency does not match the master oscillator frequency, see c.
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	If the phase error signal and the P.D.P. monitor signal (figure 19) are recognizable as a sawtooth and square wave respectively, but are asymmetric and jittering, the fast tuner system (P.D.P.-VCX) is not operating about the center of the range. If this is the case the slow tuner driver center frequency pot (figure 18 C) has to be adjusted. See (d) below.		If the phase error signal and the P.D.P. monitor signal (figure 19) are recognizable as a sawtooth and square wave respectively, but are asymmetric and jittering, the fast tuner system (P.D.P.-VCX) is not operating about the center of the range. If this is the case the slow tuner driver center frequency pot (figure 18 C) has to be adjusted. See (d) below.

	[[File:ResonatorLockStatus.jpg\|500px\|thumb\|right]]		[[File:ResonatorLockStatus.jpg\|500px\|thumb\|right\| Figure 18: R.F.C. - RF Resonator Control, S.T.C. - Slow Tuner Controller, S.T.D. - Slow Tuner Driver, P.D.P. - Pin Diode Pulser.]]

	'''Resonator Normal-conducting or Multipactoring'''		'''Resonator Normal-conducting or Multipactoring'''

Etemanson: /* Bunching System: Buncher and Chopper */

2022-08-26T16:59:15Z

Bunching System: Buncher and Chopper

← Older revision		Revision as of 12:59, 26 August 2022
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	= Bunching System: Buncher and Chopper =		= Bunching System: Buncher and Chopper =

	[[File:TimeStructureOfTheBunched.png\|500px\|thumb\|right\|Time structure of the bunched and bunched/chopped beam]]		[[File:TimeStructureOfTheBunched.png\|500px\|thumb\|right\|Time structure of the bunched and bunched/chopped beam (outdated picture, the pulses are 82.6 ns apart)]]

	The d.c. beam from the ion source is bunched into a series of pulses, about 1 ns long and 20.6 ns apart by a gridded buncher at the L.E. end of the tandem, see figures 15 (a) and 1. The residual beam, about 50% of the total, between pulses, is swept away by a parallel plate chopper at the H.E. end of the tandem, see figures 15 (b) and 1. Because the beam pulses entering the LINAC must be precisely synchronized with the R.F. in the LINAC resonators, the L.E. buncher and chopper are both actively phase locked to the LINAC 97 MHz master oscillator.		The d.c. beam from the ion source is bunched into a series of pulses, about 1 ns long and 82.6 ns apart by a gridded buncher at the L.E. end of the tandem, see figures 15 (a) and 1. The residual beam, about 50% of the total, between pulses, is swept away by a parallel plate chopper at the H.E. end of the tandem, see figures 15 (b) and 1. Because the beam pulses entering the LINAC must be precisely synchronized with the R.F. in the LINAC resonators, the L.E. buncher and chopper are both actively phase locked to the LINAC 97 MHz master oscillator.

	The chopper R.F. Is phase locked to the M.O directly. However, this would be insufficient for the L.E. buncher because the transit time of the beam pulses from the L.E. buncher to the LINAC is sensitive to the ion source pre-acceleration voltage and to the condition of the tandem. Instead, the phase of the L.E. buncher is continuously varied to keep constant the time of arrival (or phase) of the beam pulses at the beam phase detector this is located just after the LINAC 90◦ magnet, see figure 1.		The chopper R.F. Is phase locked to the M.O directly. However, this would be insufficient for the L.E. buncher because the transit time of the beam pulses from the L.E. buncher to the LINAC is sensitive to the ion source pre-acceleration voltage and to the condition of the tandem. Instead, the phase of the L.E. buncher is continuously varied to keep constant the time of arrival (or phase) of the beam pulses at the beam phase detector this is located just after the LINAC 90◦ magnet, see figure 1.

	[[File:BlockDiagramOfBucherElectronics.png\|500px\|thumb\|right\|Simplified Block diagram of buncher electronics]]		[[File:BlockDiagramOfBucherElectronics.png\|500px\|thumb\|right\|Simplified Block diagram of buncher electronics (outdated picture, upgrades include using a 12.125 MHz 4-Harmonic Generator and a digital function generator)]]

	[[File:BlockDiagramOfChopper.png\|500px\|thumb\|right\|Simplified Block Diagram of Chopper Electronics]]		[[File:BlockDiagramOfChopper.png\|500px\|thumb\|right\|Simplified Block Diagram of Chopper Electronics (outdated picture, now using a 12.125 MHz 4-Harmonic Generator)]]

	The buncher phase lock system, on its own, woks quite reliably. Unfortunately, the chopper, being located before the phase detector, makes the overall behavior more complicated. If for any reason, the beam pulses do become mis-phased by more than a ns or so, there are swept-away by the chopper and do not reach the phase detector. In this case, the phase detector still sees “pulses”, but of residual beam generated by the chopper instead. A spurious phase error signal is generated and the beam phase lock system may hang up.		The buncher phase lock system, on its own, woks quite reliably. Unfortunately, the chopper, being located before the phase detector, makes the overall behavior more complicated. If for any reason, the beam pulses do become mis-phased by more than a ns or so, there are swept-away by the chopper and do not reach the phase detector. In this case, the phase detector still sees “pulses”, but of residual beam generated by the chopper instead. A spurious phase error signal is generated and the beam phase lock system may hang up.

Etemanson: /* Resonator Lock Status */

2022-08-26T16:22:20Z

Resonator Lock Status

Rtang at 21:54, 1 May 2022

2022-05-01T21:54:46Z

← Older revision		Revision as of 17:54, 1 May 2022
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	~~<span style="color:red">'''~~NEED PROOF READING~~</span>~~		{{Warning \| NEED PROOF READING }}

	= Power Outage Procedure =		= Power Outage Procedure =

Rtang: /* Workhorse-Resonator Calibration Procedures */

2022-04-25T19:18:00Z

Workhorse-Resonator Calibration Procedures

← Older revision		Revision as of 15:18, 25 April 2022
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	Or else use phase meter.		Or else use phase meter.

			= Contact =
			* Lagy Baby mailto:lbaby@fsu.edu
			* Ingo Wiedenhoever mailto:iwiedenhoever@fsu.edu

← Older revision		Revision as of 12:22, 26 August 2022
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	= Resonator Lock Status =		= Resonator Lock Status =

	If one of the ~~Linac~~ resonators goes ‘out of lock’, its associated light on the resonator status display will illuminate. The control electronics for a resonator will generate ~~and~~		If one of the LINAC resonators goes ‘out of lock’, its associated light on the resonator status display will illuminate. The control electronics for a resonator will generate an O/L indication if the error signals in the feedback loops used to control the resonator field level or phase are excessive. After identifying the problem resonator go to the LINAC hall and check the following:

	O/L indication if the error signals in the feedback loops used to control the resonator field level or phase are excessive. After identifying the problem resonator go to the ~~Linac~~ hall and check the following:

	* Is the cryostat filling with LN2?		* Is the cryostat filling with LN2?
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	'''P.D.P. tripped on overcurrent:'''		'''P.D.P. tripped on overcurrent:'''
	First check the P.D.P. overcurrent indicator (figure 18) for the out-of-lock resonator. If illuminated push and release the red reset button on the front of the unit. This will reset the interlock and should restore the P.D.P. to normal operation. If the P.D.P. will not reset after a few attempts or continues to trip frequently call someone on the ~~Linac~~ call list for assistance.		First check the P.D.P. overcurrent indicator (figure 18) for the out-of-lock resonator. If illuminated push and release the red reset button on the front of the unit. This will reset the interlock and should restore the P.D.P. to normal operation. If the P.D.P. will not reset after a few attempts or continues to trip frequently call someone on the LINAC call list for assistance.

	'''Checking the P.D.P. for correct operational:'''		'''Checking the P.D.P. for correct operational:'''
	If the P.D.P. is not tripped the current and voltage output can be checked. First turn off the R.F. amplifier then switch the P.D.P to the ‘off’ position. 500V should be indicated and 0 current. Next switch to the ‘Auto’ position. There should be approximately 1A current and 0V indicated. If either of the above readings are not observed call someone on the ~~Linac~~ call list for help. Finally, note the present setting of the VCX gain knob on the S.T.C. then set it to minimum. You should see a clean square wave with a slight sloping top. If not, get help. Reset the VCX gain knob.		If the P.D.P. is not tripped the current and voltage output can be checked. First turn off the R.F. amplifier then switch the P.D.P to the ‘off’ position. 500V should be indicated and 0 current. Next switch to the ‘Auto’ position. There should be approximately 1A current and 0V indicated. If either of the above readings are not observed call someone on the LINAC call list for help. Finally, note the present setting of the VCX gain knob on the S.T.C. then set it to minimum. You should see a clean square wave with a slight sloping top. If not, get help. Reset the VCX gain knob.


	== Checking for proper phase lock and field level ==		== Checking for proper phase lock and field level ==

	Use the Tektronics 2445A dedicated ~~Linac~~ scope and select the recall 3 program option. The scope should be set up as follows figure 18 A and B. The time base should be set to 20 µsec. CH.1 is connected to the can mon. (100mV/div./50Ω) CH.2 is connected to the P.D.P. mon. (500mV/div./1M) CH.3 is connected to the phase error (0.1V/div.) CH.4 is connected to the P.W. clockout (0.1V/div.) trigger the scope on CH.4. For a normally operating resonator the trace illustrated in figure 19 should be observed. After setting up the scope check the following:		Use the Tektronics 2445A dedicated LINAC scope and select the recall 3 program option. The scope should be set up as follows figure 18 A and B. The time base should be set to 20 µsec. CH.1 is connected to the can mon. (100mV/div./50Ω) CH.2 is connected to the P.D.P. mon. (500mV/div./1M) CH.3 is connected to the phase error (0.1V/div.) CH.4 is connected to the P.W. clockout (0.1V/div.) trigger the scope on CH.4. For a normally operating resonator the trace illustrated in figure 19 should be observed. After setting up the scope check the following:

	First check that the resonator is operating at the proper field level. The peak-to-peak amplitude of the can mon. signal on the scope should match (±20mV) the LEV SET value for that resonator on the ~~Linac~~ control screen. Look at the monitor near the cryostat C. If the can mon. is less than the LEV SET the resonator is ‘normal’, multipactoring or the self excited loop phase control is misadjusted, see a and b.		First check that the resonator is operating at the proper field level. The peak-to-peak amplitude of the can mon. signal on the scope should match (±20mV) the LEV SET value for that resonator on the LINAC control screen. Look at the monitor near the cryostat C. If the can mon. is less than the LEV SET the resonator is ‘normal’, multipactoring or the self excited loop phase control is misadjusted, see a and b.

	If the field level is O.K. focus on the P.D.P. monitor and phase error signals:		If the field level is O.K. focus on the P.D.P. monitor and phase error signals: